JP2003500907A - Function negotiation in telecommunications networks - Google Patents

Abstract

(57) [Summary] A method for negotiating a call function between signaling points in a telecommunications system. The method includes transmitting a feature preference or a prioritized preference list from an originating signaling point to a terminating signaling point or signaling transfer point at a call control level. When the terminating signaling point or signaling transfer point accepts the preference sent by the originating signaling point, a function acceptance is returned at the call control level from the terminating signaling point or signaling forwarding point to the originating signaling point.

Description

Detailed Description of the Invention

TECHNICAL FIELD The present invention relates to capability negotiation in telecommunications networks, and in particular, but not in all cases, to the negotiation of suitable call codecs.

BACKGROUND OF THE INVENTION Currently, telecommunications networks are, to a large extent, the signaling system no. 1 as a mechanism for controlling paging connections and for handling the transfer of signaling information between signaling points of the network. 7 (SS7). Typically, one or more application and user parts of any signaling point will utilize SS7 to communicate with the peer application and user part of another signaling point. Examples of the user part are ISUP (ISDN User Part) and TUP (Telephony User Part)
So, an example of the application part is INAP (Intelligent Network)
ork Application Part) and MAP (Mobile App)
license Part). The conventional SS7 protocol stack
There are message transfer parts MTP1, MTP2, and MTP3, which handle the format of signaling messages transported over the physical layer and various routing functions.

Recently, in the telecommunications community, non-standard (
That is, there is a significant interest in using the signaling transport mechanism instead of the conventional) in the telecommunications industry to replace the conventional SS7 mechanism. The reason for this relates both to increased efficiency and potential cost savings. For example, the use of Internet Protocol (IP) networks to transport signaling information between signaling points is being actively considered. Packet resources can be effectively used for IP networks by using packet switching.
The widespread use of this technology has the advantage of low cost (compared to special telecommunications technology). We are also interested in using other transport mechanisms such as AAL1 / 2/5, FR.

The ISUP standard deals with the setup and control of call connections in telecommunications networks and is closely related to the SS7 signaling transport mechanism. Therefore, it is not suitable for using other non-standard transport technologies such as IP and AAL2. Therefore, ITU-T, ETSI, and ANSI
Some standardization organizations such as the above are currently studying a specification of a signaling protocol for call control and a specification independent of the underlying transport mechanism. This means that a protocol different from the protocol that is the bearer control function is used. Bearer control merely establishes the "pipe" parameters (including start and end points) used when transporting user plane data between nodes, and is limited to the transport mechanism. ing. In contrast, Transport Independent C
A new protocol called all Control (TICC) retains call control functionality. This function includes a service (for example, call transfer) activated to process a call between a calling side and a called side, a service related to general routing of user plane data, and the like.

As a result of separating the paging level and the bearer control level and constructing a new network architecture, an open interface is created between the paging control entity and the bearer control entity. In this interface, the above 2
The two entities are called Media Gateway Controller and Media Gateway, respectively. In the following description, this open interface is called X-CP. Examples of this are IETF MEGACO work and ITU Research Committee 16 (SG16) H.M. 248 work etc.

Traditionally, fixed telephone networks use pulse code modulation to transport user plane data (voice, facsimile, etc.) between network nodes. Current cellular networks, on the other hand, use one or more coders / decoders (called "codecs") to compress voice signals for efficient transmission over the air interface and within the cellular network. ing. If a telephone call connection spans two networks (or terminals) and they support different call codecs or multiple call codecs, the terminals can negotiate and determine the appropriate codec. . Without this negotiation, code conversion (that is, conversion from one call code to another) may have to be performed at the interface between networks. Since the code conversion uses a large amount of resources, the call quality is extremely deteriorated and the processing time is delayed. Therefore, codec negotiation is the preferred option.

In addition to codec negotiation, conventional telecommunications networks may also need to negotiate other features and parameters. For example, it may be better to negotiate security functions such as voice encryption and data encryption between terminals or nodes of a telecommunications network.

SUMMARY OF THE INVENTION According to a first aspect of the present invention, there is provided a method of negotiating a calling function between signaling points in a telecommunications system, the method comprising: from an originating signaling point to a terminating signaling point or a signaling transfer point. Sending a feature preference or prioritized preference list at the call control level, and if the terminating signaling point or signaling transfer point accepts the preferences sent by the originating signaling point, the terminating signaling point or signaling transfer point may initiate the outgoing signaling Returning the function acceptance at the call control level to the point.

In some cases, the acceptance message may not be returned, such as when the terminating signaling point or signaling transfer point does not accept the feature preference (or any of the preference lists) sent by the originating signaling point, in which case , The default function is assumed by both points. Alternatively, a default message to use the default codec may be returned. If none of the codecs reach agreement, the call may be released due to network incompatibility.

The present invention is particularly suitable for negotiating call codec functionality between signaling transfer points in different telecommunications networks. For example, in a Japanese telecommunications system, using the present invention, VSELP, PSI-CELP
, Or μ-law coding can be negotiated (μ-law coding is the default coding). However, the present invention can also be applied to the negotiation of other functions such as security functions (voice encryption, data encryption, etc.).

Although TICC can be used as a protocol for executing negotiation, CC
Specific protocols at the level (ie, user plane capability negotiation protocol) can also be used.

When the paging control level and the bearer control level are controlled by different protocols, and the selection affects the bearer level, the signaling point notifies the bearer control level to inform the selection of the function at the paging control level. respond. If it is appropriate to send a notification at the bearer level between bearer switching points, it can be sent later to establish the appropriate bearer level resources.

Preferably the signaling point or signaling transfer point is a media gateway controller. More preferably, the media gateway controller communicates with one or more media gateways present at the bearer control level.

Although some options supported for bearer control level functionality are also known at the paging control level, at the paging control level these bearer level options are not necessarily available at the moment. I don't understand. Therefore, preferably, the paging control level negotiates with the bearer control level to determine the optional availability at the bearer control level when receiving the feature preference or prioritized preference list at the terminating signaling point or signaling transfer point. More preferably, this negotiation is performed between the paging control level media gateway controller and the bearer control level media gateway.

When the prioritized preference list is sent from the originating signaling point to the media gateway controller, the controller preferably modifies the list to
Delete preferences that you know are not supported by the corresponding media gateway. The controller then sends the modified list to the media gateway, which selects the highest priority preference that the media gateway can currently support. The gateway reserves the necessary resources for its preferences and can notify the media gateway controller of the preferences. The media gateway controller can now send the capability acceptance back to the originating media gateway controller.

According to a second aspect of the present invention, a signaling point arranged to negotiate a paging function with another signaling point in a telecommunications system, wherein the function preference or prioritized preference list is a terminating signaling point. Or signaling means to the signaling transfer point at the call control level and the capability acceptance sent when the terminating signaling point or signaling transfer point accepts the preferences sent by the originating signaling point. Means for receiving at a call control level from the point, and a signaling point characterized by the following.

According to a third aspect of the present invention, a media gateway controller for a telecommunications system in which a peer or preference list of functional preferences or prioritized preferences for connections set up via the telecommunications system is peered. Means for communicating with the media gateway controller and corresponding media gateway to determine the availability of the preferences received by the media gateway, and to the peer media gateway controller according to the availability determined by the media gateway. Means for returning an acceptance message, and a media gateway controller comprising:

According to a fourth aspect of the present invention, a media gateway of a telecommunications system, wherein a feature preference or prioritized preference list for a connection set up via the telecommunications system is received from a media gateway controller. There is provided a media gateway comprising: means, means for selecting a preference content based on availability of the preference content in the media gateway, and means for transmitting the selected preference content to the media gateway controller.

According to a fifth aspect of the present invention, protocol options are negotiated between first, second and third nodes in a telecommunications network using separate call control protocols and bearer control protocols. A method comprising: sending a first call control message from a first node to a second node specifying protocol options supported by the first node; and both the first and second nodes. Sending a second call control message specifying a protocol option to support from the second node to the third node, and selecting a protocol option from the protocol options specified in the second control message. A method comprising:

The step of selecting a protocol option from the protocol options specified in the second control message can be performed at the third node.

Each call control message may include a preference level corresponding to each specified protocol option.

The first node can be the originating node and the third node can be the terminating node.

The method determines whether the bearer level between the first node and the second node is affected by the selecting step, and if the bearer level is affected, the first node and the second node The method may further include performing an action to modify bearer level parameters between the two nodes.

The method also determines whether the bearer level between the second node and the third node is affected by the step of selecting and, if the bearer level is affected, the second node. The method may further include performing an action of modifying a bearer level parameter between the third node and the third node.

According to a sixth aspect of the invention, there is provided a method of setting up a call paging connection in a telecommunications system in which a paging control protocol is independent of a bearer transport mechanism, the method comprising: Negotiating a first call codec with a terminating signaling point of the call, and a paging connection via a transport mechanism between the originating signaling point and the first terminating signaling point according to the first call codec. Establishing a second call codec between the first terminating signaling point and the second new terminating signaling point, and then a second different call codec to the originating signaling point. To notify Establishing a paging connection between the originating signaling point and the second terminating signaling point, the first originating signaling point acting as an intermediate signaling point, the first paging connection Is modified as needed to support the second call codec, and a method is provided.

Embodiments of the present invention modify the connection between the originating signaling point and the original termination signaling point to reflect the new codec, thereby facilitating transfer of the paging connection between different termination signaling points. To do so. The final end-to-end connection is completed by establishing a connection between the original end signaling point and the new end signaling point according to the new codec.
Preferably, the latter connection is established after modifying the first connection, even if it is not necessary.

In addition, the method of the present invention is the result of the call codec negotiation between the original terminating signaling point and the final terminating signaling point.
Applicable only when the call codec is not specified. If the result is the first call codec, the original connection may not need to be modified.

[0028] Preferably, informing the originating signaling point of the second call codec comprises sending an appropriate call control (CC) message from the original terminating signaling point to the originating signaling point. This CC message may be a "correction.request message".

Preferably, the call control protocol is Transport Independent Call Control (TI).
CC) protocol.

The present invention can be applied to the evolution of existing telecommunications networks such as mobile networks based on GSM, DAMPS, PDC, etc., and also to future generation networks such as UMTS.

According to a seventh aspect of the present invention, a telecommunications system in which a call control protocol is independent of the bearer transport mechanism, between the originating signaling point and the first terminating signaling point of the system. Means for negotiating a first call codec, means for establishing a call connection via a transport mechanism between an originating signaling point and the first terminating signaling point according to the first call codec, Means for later negotiating a second different call codec between the first end signaling point and the second new end signaling point, and means for notifying the originating signaling point of the second call codec, Originating Signaling Point and Said Second Termination Signalin Means for establishing a paging connection with a point, said first originating signaling point acting as an intermediate signaling point, said first paging connection being required to support said second call codec. And a means to be modified according to the present invention.

According to an eighth aspect of the present invention, a call control protocol is a signaling point of a telecommunications network in which the bearer transport mechanism is independent, wherein the first terminating signaling point and the first call codec are Processing means for negotiating; means for establishing a paging connection between a calling signaling point and the first terminating signaling point via a transport mechanism according to the first call codec; and the first terminating signaling point. Means for receiving a notification of the second call codec negotiated between the second call signaling point and a second new terminating signaling point; and for supporting the second call codec, the first call connection optionally Means for modifying, and signaling comprising: To provide a Into.

According to a ninth aspect of the invention, a method of setting up a paging connection between a first and a second mobile telephone network, wherein either network is outside the radio access network part of the mobile network. A method comprising an installed tandem free operation (TFO) device, wherein the call control protocol is independent of the bearer transport mechanism, said TFO device of one mobile network in order to determine the appropriate call codec. Performing a negotiation with a peer TFO device on the other mobile network, and notifying the radio access network of the determined call codec by sending a call control (CC) message from the corresponding TFO device. And including And a method characterized by:

Each mobile network may include a tandem free operations (TFO) device outside the radio access network portion of the mobile network. However, this is not always the case and in either mobile network there may be a TFO in the radio access network.

The two mobile telephone networks can be linked together via the PSTN.
Preferably, the negotiation is performed using a TFO protocol codec mismatch resolution and optimization procedure and the TFO message is transmitted using in-band signaling.

Preferably said or each TFO installed outside a radio access network
The device is installed in a gateway MSC (GMSC) that provides an interface between a mobile network and an external network (such as PSTN).

The present invention is particularly suitable for setting up call connections between subscribers, any of which are subscribers of a Universal Mobile Telecommunications System (UMTS) network. In this case, the radio access network is preferably a UMTS terminal terrestrial radio access network (UTRAN) and the T
The FO device is installed at the boundary of the UMTS core network.

According to a tenth aspect of the invention, an apparatus for setting up a call connection between first and second mobile telephone networks, wherein at least one network is outside the radio access network part of the mobile network. A tandem free operation (TFO) device installed in the mobile communication system, wherein the call control protocol is independent of the bearer transport mechanism, the TFO device of one mobile network for determining an appropriate call codec. And means for performing negotiation between the peer TFO device of the other mobile network, and notifying the radio access network of the determined call codec by sending a call control (CC) message from the corresponding TFO device. And means A device characterized by the above.

According to an eleventh aspect of the present invention, a method of setting up a call connection between a first and a second mobile telephone network, each network being installed outside a radio access network part of the mobile network. Tandem free operation (TFO) device, the call control protocol is independent of the bearer transport mechanism, and both mobile networks are public switched telephone networks (PS).
TN) and performing a negotiation between two mobile terminals respectively subscribed to the first and second mobile networks to determine an appropriate call codec. Wherein the negotiation is carried out using a call control protocol signaling message exchanged between the radio access network part and each TFO device and an ISUP message transmitted between the TFO devices. Provide a way.

For example, the list of codecs available on the originating mobile network can be sent from the TFO device of that network to the peer TFO device using an ISUP Initial Address Message (IAM). The message may further include a codec preferred by the originating mobile network. Subsequent ISUP messages sent in the reverse direction indicate the codec type selected by the terminating mobile terminal. The ISUP standard may have to be modified to enable this negotiation procedure.

According to a twelfth aspect of the invention, an apparatus for setting up a call connection between a first and a second mobile telephone network, each network being installed outside a radio access network part of the mobile network. Tandem free operation (TFO) device, the call control protocol is independent of the bearer transport mechanism, and both mobile networks are public switched telephone networks (PS).
TN) means for performing negotiation between two mobile terminals, respectively subscribing to the first and second mobile networks, in order to determine an appropriate call codec. And the negotiation is based on the radio access network part and each T
Call control protocol signaling messages and TFs exchanged between FO devices
O means for performing using ISUP messages transmitted between the devices.

Detailed Description of the Embodiments FIG. 1 shows a part of a telecommunications network including two signaling points, referred to as node A and node C in the following description. These nodes are telephone exchanges or switches, and may belong to the same network operator or different network operators. In the following example, node A represents the originating node to which the caller (not shown) is connected and node C represents the end node to which the callee is connected. Each signaling point is composed of a call control (CC) part and a bearer control (BC) part. That is, the call control function and the bearer control function are separated into two different protocol layers. The CC portion forms the call control level and performs functions such as call forwarding and other routing and control functions. The BC parts establish a pipe between the BC parts to determine their size and transport the user plane data.

Explaining the BC level, this level is configured by a bearer network such as an IP network. One bearer switching point (
Although only Node B) is shown, there are one or more bearer switching points in the IP network. In the case of IP networks, these bearer switching points are IP routers. If the bearer network is an ATM network or an AAL2 network, this bearer switching point will be an ATM switch or an AAL2 switch, respectively.

When the caller initiates a call by picking up the handset or the like, node A, which is the originating signaling point, receives information at the CC level from the source (caller).
This information defines the bearer resource request. The originating signaling point determines the available option list that needs to be negotiated with the terminating signaling point, Node C, based on either the source information or the capabilities of the signaling point and its home network (or both).

Next, the node A inserts the available option list into the message and sends a signal to the CC portion that negotiates a specific function (node C in FIG. 1). This message indicates the preference level for each option.

Node C uses the priority level specified by node A for each option in the list and selects the option with the highest preference level among the options it supports. That is, node C selects only the highest preference option, even though node A supports another option in the list that has a high preference. Node C sends the selected options to Node A.

When the result of this negotiation affects the bearer connection level, appropriate measures are taken at the bearer level so as to match the result of the negotiation. This is done with the BC protocol. There are two cases: forward bearer modification (Case A in FIG. 2) and reverse bearer modification (Case B in FIG. 2).

An example of a feature that can be negotiated using the above method is a codec feature. Generally, in wireless access networks, calls are transcoded to PCM. This is because this is the only call format that can be used in conventional fixed telephone networks. However, since the code conversion process extremely deteriorates the call quality, some compatible cellular standards (GSM, PDC, etc.)
For example, the specification defines a method for avoiding code conversion when a connection is established between two GSM terminals used with a common codec. Although most current mobile terminals support some codecs, these methods also enable codec negotiation, but there are some serious deficiencies when compared to the generic negotiation mechanism shown below.

Is the call codec tightly coupled to the mobile environment? (In PDC, the codec negotiation is Mobile Application Part (MA).
P) is a service of the protocol) or it does not optimize the use of hardware and transmission resources (in GSM, codec negotiation is part of tanden free operation). Two transcoders (TRAUs) and 64 Kbps channels are always allocated for call connections, regardless of whether transcoding is actually performed. Currently, various mobile standards deal with this issue in different ways, and so far there was no possibility to coordinate these solutions.

Another example of a function that requires negotiation is a security function (voice encryption,
Data encryption). Currently this is a major concern in public telecommunications networks and will become even more important in the near future. However, there are several ways to protect a user's plain information from unwanted third parties. There are multiple cryptographic algorithms, and the data cryptographic algorithms currently under development and new algorithms are being introduced one after another. Therefore, a method for negotiating security features in public telecommunications networks will be needed in the near future, and this method is provided by the present invention.

The above description refers generally to BC and CC levels. FIG. 3 illustrates the telecommunications system split into CC and BC levels in more detail. CC level has multiple media gateway controllers (M
GC_A, MGC_B, MGC_C), and the BC level includes a plurality of media gateways (MG_1 to MG_6). The first pair of media gateways (MG_1, MG_6) is a bearer connection via the AAL2 network and the second pair of media gateways (MG_2, MG_5) is a bearer connection via the IP network. Third pair of media gateways (MG
_3, MG_4) is a bearer connection via the STM network. As is clear from FIG. 3, each media gateway controller is arranged to control two or three media gateways via open interfaces (X-CP_1 to X-CP_3).

As already explained above, the capability negotiation is at CC level, ie
Between media gateway controllers. In addition, X-CP is also used as a means for the media gateway to "notify" the controlling media gateway controller of the features and options supported by the media gateway (eg, feature = compressed call, option = codec list). ). Also, the media gateway can participate in negotiations via X-CP, so that function selection depends not only on the functions specified in the gateway, but also on whether these functions are currently available. Without this configuration, there is a risk that the media gateway will not have the resources to support the options that the media gateway controller has negotiated for the media gateway. For example, consider the case where a media gateway controller needs to provide an intelligent network (IN) service for a call, and the service requires in-band announcement information. If the media gateway controller alone selects a codec according to its knowledge of the codecs that the media gateway supports, the media gateway may not currently have TRAU available for this codec. Therefore, the media gateway rejects this connection and the call is aborted.

To illustrate the solution to this problem, consider the case where a media gateway controller receives a connection setup message from a peer media gateway controller that contains an option list for a particular negotiable feature. The message indicates the preference level for each option. The receiving media gateway controller reads the received list and removes from the list any options known to be unsupported by the media gateway selected for the connection. The media gateway controller then sends the modified option list to the media gateway via the X-CP interface.

The receiving media gateway selects the option with the highest priority and which the gateway can currently support. The media gateway then obtains the resources needed to support this option and sends the option to the media gateway controller via the X-CP interface. Upon receiving the selected option, the media gateway controller sends the selected content to the peer media gateway controller as described above.

The generic function negotiation described above will be described in more detail with reference to the flow chart of FIG.

In many countries, merchants are required by their national authorities to intercept calls for legal purposes. To enable legitimate interception, merchants typically use user plane data (ie,
It requires all access to the actual call, or other data sent by the so-called "pipe" that takes place at the bearer level. By introducing TICC,
User plane data can be transported via various techniques (ATM, IP, etc.), which also enables transport of encrypted user plane data. Therefore, if the legitimate interception point cannot determine the security and codec (encryption and decryption) characteristics of the user plane data, the call cannot be intercepted normally. Therefore, the merchant needs knowledge of the codec and cryptographic (security) algorithm used in each BC section of the call (between two BC nodes).

On the other hand, the code conversion and conversion processing of the security algorithm significantly deteriorate the quality of service of the call and cause an extra delay. Therefore, reduce (if possible avoid) the number of conversion points required end-to-end for each call,
It is desirable to reduce the conversion of security algorithm points.

A mechanism for solving this problem will be described with reference to the operation sequence of FIG. The call control portion of node A (see FIG. 1) sends a message to the call control portion of node B. This message contains a list of options that node A supports and the preference level for each option. This mechanism is particularly suitable for use with TICC, but can also be used with independent protocols specially adapted for performing negotiation. This is the acronym UPCN (User Par) in FIG.
t Capability Negotiation).

Next, the call control side of node B sends a message to the call control side of node C. It contains a list of options supported by both Node A and Node B and a preference level for each option. Node C selects the highest preference level of support options and returns a message containing the selected options to Node B. Upon receiving this message, node B sends a message specifying the selection option to node A.

Next, FIG. 5 shows two operation sequences labeled as case A and case B. In case A, when the bearer level is affected by the call control level negotiation described above, node A will take appropriate action at the bearer level. For example, node A may have to resize the pipe needed to support the selected option. A BC message is then sent from node A to node B, specifying which parameters are needed. The Node B then analyzes the options selected and, if the bearer level is affected by the negotiation, takes appropriate action at the bearer level. The BC message is then sent from Node B to Node C, specifying which parameters are required at the bearer level between Node B and Node C.

In case B, the bearer-level operational sequence starts at node C and ends at node A
end with. Node C analyzes the selected option and takes appropriate action at the bearer level if the bearer level is affected by the negotiation.
Next, a BC message is sent from node C to node B, specifying the required parameters. The Node B analyzes the selected option and takes appropriate action at the bearer level if the bearer level is affected by the negotiation. A BC message is then sent from node A to node B, specifying the required parameters.

Case A and Case B are alternatives, but other cases are possible. In this regard, the BC protocol between node A and node B may be different from the protocol between node B and node C. For example, the protocols may be ATM and IP, respectively. It may be necessary to modify the bearer level connection parameters between one node pair, but not between the other node pair.

The above negotiation can be performed at the time of call establishment or at the time of call.
The latter applies, for example, when the user wants to start using cryptography when calling.

This procedure can reduce the number of points in the network where generic functions need to be changed. In particular, the mechanism specified above can be used to minimize the number of code conversion points or security algorithm point conversions for end-to-end calls across multiple CC sections. This solution is 1
Applicable to calls across one or more networks.

The GCN mechanism also includes the ability to have the option list and its preference levels built into the initiating CC node and use the preference level indicated by the originating node to allow the terminating node to select support options. The negotiation mechanism described below is useful only when the negotiation is performed between two CC nodes. The proposed adaptation method extends this GCN mechanism when multiple CC nodes intervene in the negotiation. That is, a call spans multiple CC nodes belonging to one or more telecommunications carriers. This adaptation method includes the following operation sequence. 1. The initiating CC node sends a list of supported options and a preference level corresponding to each option. 2. The relay CC node analyzes the received option list, removes the unsupported option from the list and forwards the list to the next node. 3. The terminating CC node analyzes the received option list and the corresponding priorities and selects the highest priority support option shown.

In the case of legal interception, the legal interception point (that is, the node where the interception takes place) can receive the security and coding characteristics of the user plane data so that the call can be intercepted normally.

In the proposed new architecture shown in FIG. 1, the call control protocol is independent of the transport mechanism. In this case, the TICC must establish a user plane transport connection for the call without performing codec negotiation on the call. The reason is that the amount of transport resources needed to support a call depends on the codec selected for the call (ie the result of the codec negotiation procedure). In some cases, the codec is initially selected for the call, but due to changes in the environment, this codec must be changed to the new codec in the latter phase of the call. Two important cases in which this situation occurs are: 1) Intelligent network (I) to perform announcement information and to redirect the call to the called party either automatically or according to input from the calling party.
N) Interaction with the service. This requires selecting the first codec in order to carry out the announcement information. Later, the call is transferred / retransferred to the other party and the second codec is used. 2) This is a so-called supplementary service, Call Forwarding on
No-Reply (CFNR). After negotiating the first codec between side A and side B, it forwards the call to side C because B does not answer within a predefined time. The second codec is required according to the request from the C side.

In cases 1) and 2) above, and other cases related thereto, it is necessary to establish a paging connection with the transport mechanism by the first selected codec and perform announcement information, signal tone check, etc. . If the codec changes later, the call connection may need to be modified to support the new codec.

In the following, referring to FIG. 6, a signaling process used in a network using the TICC protocol and capable of establishing an end-to-end telephone connection for a call is described. Here, the call is generated at the originating signaling point, Node A, and is first transferred to the first node, Node B, or the signaling point. This call is then forwarded to another terminating signaling point, node C. The illustrated process relates specifically to an IN service call, in which the caller is first connected to an IN network node, which plays the prerecorded message to the caller and then terminates the call. It is to be transferred to the signaling point. Also, the illustrated process involves a CFNR service, in which case the caller connected to the first end signaling point does not answer the call, but forwards the call to the new end signaling point.

The signaling sequence consists of the following sequential steps. 1. Node A establishes a call to node B. Select codec X for this call. 2. A transport connection with transport resources appropriate for the selected codec is set up between node A and node B. 3. Node B transfers / retransfers the call to node C. Node C does not support codec X and selects codec Y. 4. Node B requests node A to modify the codec selection for this call from codec X to codec Y. 5. Match the transport connection between node A and node B to codec Y,
Correct if necessary. FIG. 6 shows the case where the modification to the transport connection is made in the forward direction and the alternative case where the modification is made in the reverse direction. 6. A suitable transport connection for Codec Y is established between Node B and Node C. 7. The TICC completes the call establishment (TICC ACM + TICC AN
M).

Since TICC is based on ISUP, the signaling message name is I
Taken from SUP. However, since ISUP does not include a codec negotiation procedure or a codec modification procedure, a new TICC message pair ("TICC modification.request / confirm") is required to perform the codec modification function.

Although FIG. 6 shows that only the modifications made for the transport connection from node A to node B are made in the forward or reverse direction, other transport connection modifications are also made in the forward or reverse direction. Can be done in the direction. Also, transport connections can be established in the forward or reverse direction.

The mechanism described above can be used to establish a call ringing connection between four or more signaling points or nodes. For example, between the node A that is the originating signaling point and the node B that is the original termination signaling point, or between the node B that is the original termination signaling point and the node C that is the final termination signaling point (or its There may be one or more relay nodes in both). The call may also be forwarded or relayed from node C to yet another signaling point (ie node D). However, in this case, a negotiation is required to determine whether the codec Y is suitable for the node D. If not, transport between the node A and the node B and between the node B and the node C is required. The connection may need modification. This process can be extended to any number of nodes.

The conventional public switched telephone network (PSTN) digitally encodes call data for transfer using pulse code modulation (PCM). Digital mobile telephone networks, on the other hand, use more advanced coding techniques such as CELP and adaptive multi-rate (AMR) coding to achieve higher compression rates than PCM. In many mobile networks, call coding and decoding is done by the mobile terminal itself. When making a call with two mobile terminals registered on the same network, it is possible to send the coded call data end-to-end.

When a call is made from a mobile terminal registered to the mobile network to a terminal that is a subscriber of the “foreign” network, the end-to-end transmission of the coded call data depends on the characteristics of the external network and the origination. Depending on the characteristics of the intermediate network connecting the mobile network to the external network, this may not be possible (of course this also applies if the call originates on the external network).

Considering the telecommunications system of FIG. 7, this system is composed of two third generation Universal Mobile Telecommunications System (UMTS) networks 1 and 2, which are conventional PSTN / It is connected by the ISDN network 3. The UMTS networks 1 and 2 each include a UMTS terminal terrestrial radio connection network (UTRAN) 4, which is composed of a radio network controller (RNC) 5 and a radio base station (BTS) 6. The UTRAN 5 passes compressed call data between a mobile terminal (not shown) and a mobile switching center (MSC) 7 which forwards incoming and outgoing call connections.

A call originates from a subscriber of one UMTS network 1 and another UMTS network 1
The call shall be sent to a subscriber of network 2. Call is UMT
Each relay node 8 of the S networks 1 and 2 (one of which is the gateway MSC (GM
SC)) and is transferred via PSTN3. As already described above, PSTN3 uses PCM to encode call data. It is important that the call data transferred via PSTN3 be in a format understandable by the network. For example, the PSTN 3 may insert the notification information of the trader into the call, execute the voice prompt service, etc.
Necessary to allow the third party to monitor calls for security purposes and the like. Therefore, before passing the data to PSTN3, the UMTS network 1
It is necessary to “transcode” the call data with the GMSC 8 of No. 2 and No. 2. That is, the call data is converted from the mobile network call coding format to PCM. Similarly, the PCM data received by the GMSC 8 needs to be converted into the corresponding mobile network call coding format.

When the code conversion is executed, the GMSC 8 consumes a large amount of processing resources, and the deterioration of the call quality is also noticeable. To partially compensate for these drawbacks, a tandem free operation (TFO) device can be introduced into the call connection in the GMSC 8. The outgoing call data is still converted to PCM, but the least significant bit of each PCM sample is "sniffed" by the TFO device. The bandwidth of the channel formed by these eavesdropping bits is sufficiently large (ie 8 Kbits / sec) to transmit the original coded data. The TFO device of the terminating UMTS network assembles the coded data and sends it to the corresponding UTRAN, but the received PCM data is discarded (the PSTN modifies the data by adding notification information of the vendor, etc.). Unless you have). In this way, the TFO makes the PCM data available to the PSTN 3, but the end-to-end transmission of effectively coded call data can still be performed.

When an intermediary device in the PSTN / ISDN modifies the PCM bitstream, T
The FO device detects the change and "falls back" to pass the PCM coded call between the TFO devices. That is, the compressed audio data is not passed thereafter.

The call codec that can be used by the mobile network depends on the characteristics of the network and, in some cases, the characteristics of the terminal using the network. Obviously, a single codec can be used end-to-end only when the two networks both use the same codec. Assuming that the GMSCs of the two mobile communication networks have knowledge of the codec capabilities of the connecting network, it is possible to negotiate them and agree to use a common codec. In fact, the ETSI recommendation GSM 08.62 (version 7.0.0, release 1998) provides a suitable protocol.

When the TFO device is installed at the boundary of the mobile network, that is, outside the UTRAN as shown in FIG. 7 (traditionally, the TFO device is installed in the radio access network), the TFO is executed in the mobile network. If you try, you'll have problems. Currently, in such networks there is no exchange information about the codecs negotiated between TFO devices and between TFO devices and radio access networks.

FIG. 8 shows a modified system architecture in which the GMSC of two UMTS networks incorporate a TFO device 9. On the other hand, FIG. 9 shows signaling for call setup between two nodes in each UMTS mobile telephone network. Nodes 1 and 4 represent MSCs and the two intermediate nodes 2 and 3 represent GMSCs.

Call setup signaling in the UMTS network is done at the call control (eg TICC) level. This call setup is MSC
From the corresponding GMSC to the corresponding GMSC. This IAM uses a Generic Capability Negotiation (GCN) mechanism to determine the number of parameters for a paging connection. In particular, the IAM contains a codec list and preferred codecs supported by the originating UMTS network. Calling side GM
The SC selects the codec from the transmitted codec list, and
Message (selected codec 1) ”to the MSC. afterwards,
The paging connection is established at a bearer level (eg AAL2 or IP) with sufficient bandwidth to support the selected codec.

It has been proposed to add GCN to the ISUP protocol in order to be able to perform end-to-end codec negotiation. This end-to-end codec negotiation increases the probability that both endpoints will use the same codec type. If both endpoints use the same voice coding algorithm, the TFO can pass the compressed voice over the PCM network without causing unnecessary voice quality degradation. It also reduces bearer requirements in the originating and terminating networks that support compressed voice (eg, AAL2 or IP bearer transport), so less transmission is required.

FIG. 9 illustrates the use of GCN Enhancement ISUP messages to bridge signaling “gaps” between two UMTS networks. In the terminating UMTS network, IAM is sent from GMSC to MSC using TICC. In this case, the MSC accepts the use of Codec 1 and informs TICC of that fact.
And send back to GMSC. Then bearer level connection is terminated to UMTS
Established in the network. The PSTN confirms that the codec is accepted by the originating GMS.
Relay to C. There is no need to change the bearer level connection in the originating UMTS network since the originally proposed codec was accepted. However, when there is a change in the codec, it is necessary to send a message to that effect from the originating GMSC to the MSC. As a result, the bearer level connection can be modified and the connection bandwidth can be expanded. In FIG. 9, the ACM is the Address Complete Me.
message (address completion message), ANM is Answer Mes
The message (response message) is shown.

FIG. 10 illustrates a second embodiment of the present invention. This solution is TF
Use the optional codec mismatch resolution and optimization procedures provided in the O protocol to detect incompatible codecs. When the TFO detects a codec incompatibility, it can initiate a codec modification procedure to modify the codec used by the terminal. The TFO specifies the rules for resolving codec mismatches (ie, which codec to select). The TFO protocol then initiates TICC signaling, modifies the codec used in the call and enables compatible codecs at the two end terminals. If the originating UMTS network changes from the first codec shown to another codec, it may be necessary to modify the bearer level connection established in both UMTS networks.

The embodiments described above minimize unnecessary call transcoding by intermediate PCM networks, and also to support service levels of particular calls in public telecommunications networks, user plane devices (eg, Optimize the allocation of transcoders) or user plane resources (eg bandwidth) (or both).

Codec type negotiation is required when existing and new networks support only PCM coded voice to minimize unnecessary transcoding in the call path. UMTS and GSM subscriber call quality does not necessarily degrade when calls pass through existing PCM core networks with TFO support capabilities. Incorporating the GCN mechanism into the TICC protocol is often done in a transparent fashion (APM users).

It will be apparent to those skilled in the art that various modifications can be made to the above embodiments without departing from the scope of the invention.

[Brief description of drawings]

[Figure 1]   FIG. 5 shows a plurality of signaling points in a telecommunications network.

2 (Case A) is a diagram showing a signaling flow between the signaling points of FIG. 1 according to the first embodiment of the present invention.

2 (Case B) is a diagram showing a signaling flow between the signaling points of FIG. 1 according to a second embodiment of the present invention.

FIG. 3 shows a telecommunications network including a media gateway controller and a media gateway.

4 is a flow diagram illustrating a generic capability negotiation process used in the network of FIG.

FIG. 5 is a diagram showing a signaling flow in which an intermediate node is involved in negotiation between an originating node and a terminating node.

FIG. 6 shows another set of signaling flows in which an intermediate node is involved in negotiation between an originating node and a terminating node.

[Figure 7]   FIG. 1 schematically shows a telecommunication system of known design.

[Figure 8]   It is a figure which shows a telecommunications system typically.

9 is a first signal set according to the first embodiment of the present invention relating to codec negotiation of the system of FIG.

10 is a second signal set according to a second embodiment of the present invention relating to codec negotiation of the system of FIG.

[Procedure for Amendment] Submission for translation of Article 34 Amendment of Patent Cooperation Treaty

[Submission date] May 18, 2001 (2001.5.18)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Contents of correction]

[Claims]

6. A method according to any one of the above claims, signaling point or signaling transfer point, and characterized in that it comprises a media gateway controller in communication with one or more media gateways Bearer Control level how to.

7. A method according to any one of the above claims, when receiving the function preference or prioritized preferences list at the end signaling point or signaling transfer point, the Call Control level bearer control level negotiating A method of performing to determine option availability at a bearer control level.

8. A method according to claim 7 when dependent on claim 6 ,
The method according to claim 1, wherein the negotiation is performed between a paging control level media gateway controller and a bearer control level media gateway.

9. The method of claim 8, when the prioritized preferences list is sent from an originating signaling point to the media gateway controller, the controller to modify the list, corresponds to the Media Gateway Support It deletes the preferences that it knows are not present and sends the modified list to the Media Gateway, which selects the highest priority preference that the Media Gateway can currently support, and the Gateway secures the resources it needs. , A method of notifying a media gateway controller of preferences.

10. A signaling point arranged to negotiate a paging function with another signaling point in a telecommunications system in which the paging control level and the bearer control level are controlled by different protocols , wherein the paging function is prioritized or prioritized. Means for sending the preference list to the terminating signaling point or signaling transfer point at the call control level, and the capability acceptance sent if the terminating signaling point or signaling transfer point accepts the preferences sent by the originating signaling point, Means to receive at the call control level from the terminating signaling point or signaling transfer point and, if the selection affects the bearer level, select the function at the call control level by notifying the bearer control level And a means for responding to the signaling point.

11. A media gateway controller of a telecommunication system call control level and bearer control levels are controlled by separate protocols, the function preference or prioritized preferences list of connections set up via the telecommunication system , A means for receiving from a peer media gateway controller, a means for communicating with a media gateway corresponding to the media gateway controller and determining the availability of preferences received by the media gateway, and a means for determining the availability of the peer according to the availability determined by the media gateway. A means for returning a function preference acceptance message to the media gateway controller, and a media gateway controller.

12. A media gateway for a telecommunications system in which a paging control level and a bearer control level are controlled by different protocols , the feature or prioritized preference list relating to a connection set up via the telecommunications system, A media gateway comprising: means for receiving from the media gateway controller; means for selecting a preference content based on availability of the preference content in the media gateway; and means for transmitting the selected preference content to the media gateway controller.

13. The telecommunications network using a separate call control protocol and bearer control protocol, first, a second, and a third method of negotiating protocol options between nodes, the first node A first call control message specifying a protocol option supported by the first node to the second node, and a second specifying a protocol option supported by both the first and second nodes. Sending a paging control message from the second node to the third node, and selecting a protocol option from the protocol options specified in the second control message.

14. The method of claim 13 , wherein the step of selecting a protocol option from protocol options specified in the second control message is performed at a third node. .

15. The method of claim 13 or 14, wherein each call control message, wherein it contains the preference level for each protocol options specified.

16. A method according to any of claims 13 to 15, a method of the first node characterized in that it is a source node.

17. A method according to any of claims 13 to 16 , characterized in that the third node is a terminal node.

18. A method according to any of claims 13 17, to determine whether the bearer level between the first node and the second node is affected in said selecting step, The method further comprising performing an action to modify bearer level parameters between the first node and the second node if the bearer level is affected.

19. A method according to any of claims 13 18, to determine whether the bearer level between the second node and the third node is affected in said selecting step, If the bearer level is affected, the method further comprises performing an action of modifying a bearer level parameter between the second node and the third node.

20. A method of setting up a call paging connection in a telecommunications system wherein a paging control protocol is transport mechanism independent, the method comprising: a first signaling point between a system's originating signaling point and a first terminating signaling point. The call codec of the first call signaling point, and the step of establishing a paging connection between the originating signaling point and the first terminating signaling point via a transport mechanism according to the first call codec. Between the terminating signaling point and the second new terminating signaling point, then negotiating a second different call codec, notifying the originating signaling point of the second call codec, and the originating signaling point. Establishing a paging connection between the second call signaling point and the second terminating signaling point, the first originating signaling point acting as an intermediate signaling point, and the first paging connection being the second call. A step of modifying as necessary to support the codec, the method comprising:

21. The method according to claim 20 , wherein the first call connection is modified so that a transport connection between an original termination signaling point and a new termination signaling point is later modified according to a new codec. A method comprising the step of establishing.

22. A method according to claim 20 or 21, suitable call control from the original termination signaling point to the originating signaling point (CC)
Informing the originating signaling point of the second call codec by sending a message.

23. The method of claim 22 , wherein the call control protocol is a Transport Independent Call Control (TICC) protocol and the CC message is a "Modify.Request" message.

24. A telecommunication system call control protocol is independent of the transport mechanism, between the originating signaling point and the first end signaling point of the system, means for negotiating a first speech codec And means for establishing a paging connection via a transport mechanism between an originating signaling point and the first terminating signaling point according to the first call codec, the first terminating signaling point and the second terminating signaling point. Means for later negotiating a second different call codec with the new terminating signaling point, means for notifying the originating signaling point of the second call codec, originating signaling point and said second terminating signaling Make a call connection with the point Means for establishing the first outgoing signaling point acting as an intermediate signaling point, the first paging connection being modified as necessary to support the second call codec, A system characterized by comprising.

25. A telecommunications network signaling point, the call control protocol of which is independent of the transport mechanism, the processing means negotiating a first end signaling point and a first call codec; Means for establishing a paging connection between a calling signaling point and the first terminating signaling point via a transport mechanism according to a call codec; and the first terminating signaling point and the second new terminating signaling point. Means for receiving a notification of the second call codec negotiated between the two, and means for modifying the first call connection as needed to support the second call codec. Signaling point to be.

26. A method for setting up a call connection between the first and second mobile telephone network, any network tandem free operation which are located outside of the radio access network part of the mobile network (TFO) A device, wherein the call control protocol is independent of the bearer transport mechanism, wherein the TFO device of one mobile network and the peer TFO device of the other mobile network are used to determine the appropriate call codec. Performing a negotiation between the two, and notifying the radio access network of the determined call codec by transmitting a call control (CC) message from the corresponding TFO device. Method.

27. The method of claim 26, each mobile network, wherein the containing tandem free operation (TFO) devices on the outside of the radio access network part of the mobile network.

28. A method according to claim 26 or 27, the two mobile telephone networks, the method being characterized in that coupled to one another via the PSTN.

29. A method according to any of claims 26 28, wherein the negotiation is a method of using a codec mismatch resolution and optimization procedure of TFO protocol, TFO messages using in-band signaling And then send.

30. The method according to any of claims 26 to 29 , wherein said or each TFO device installed outside a radio access network provides an interface between a mobile network and an external network. (GMSC).

31. A method according to any of claims 26 to 30, Tandem Free Operation (TFO) devices wireless access network that is installed outside the network part is a Universal Mobile Telecommunications system (UMTS) network Wherein the radio access network is a UMTS terminal terrestrial radio access network.

32. An apparatus for setting up a call connection between first and second mobile telephone networks, at least one of which is located outside the radio access network portion of the mobile network in tandem free operation (TFO). ) A device whose call control protocol is independent of the bearer transport mechanism, said TFO device of one mobile network and a peer TFO device of the other mobile network in order to determine the appropriate call codec. And a means for notifying the radio access network of the determined call codec by transmitting a call control (CC) message from the corresponding TFO device. Device to do.

33. A method for setting up a call connection between the first and second mobile telephone networks, a tandem-free operation each network that is installed outside the radio access network part of the mobile network (
TFO) device, the call control protocol is independent of the bearer transport mechanism, and both mobile networks are connected via the public switched telephone network (PSTN) to determine the appropriate call codec. In order to carry out a negotiation between two mobile terminals respectively subscribed to the first and second mobile networks, the negotiation being exchanged between the radio access network part and each TFO device. Performing using a call control protocol signaling message and an ISUP message sent between TFO devices.

34. The method of claim 33 , wherein a list of codecs available on an originating mobile network is transmitted from a TFO device of the network to a peer TFO device using an ISUP Initial Address Message (IAM). , Sending the selected codec back to the originating network in a subsequent ISUP message.

35. The first and a device for setting up a call connection between the second mobile telephone network, a tandem-free operation each network that is installed outside the radio access network part of the mobile network (
TFO) device, the call control protocol is independent of the bearer transport mechanism, and both mobile networks are connected via the public switched telephone network (PSTN) to determine the appropriate call codec. Means for performing a negotiation between two mobile terminals respectively subscribed to the first and second mobile networks, the negotiation comprising a radio access network part and each T
Call control protocol signaling messages and TFs exchanged between FO devices
O means for performing using ISUP messages transmitted between devices.

─────────────────────────────────────────────────── ─── Continued front page    (31) Priority claim number 9914700.1 (32) Priority date June 23, 1999 (June 23, 1999) (33) Priority claim country United Kingdom (GB) (31) Priority claim number 9915366.0 (32) Priority date July 2, 1999 (July 1999) (33) Priority claim country United Kingdom (GB) (31) Priority claim number 9921647.5 (32) Priority date September 15, 1999 (September 15, 1999) (33) Priority claim country United Kingdom (GB) (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, SD, SL, SZ, TZ, UG, ZW ), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, C N, CR, CU, CZ, DE, DK, DM, DZ, EE , ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, K P, KR, KZ, LC, LK, LR, LS, LT, LU , LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, S G, SI, SK, SL, TJ, TM, TR, TT, TZ , UA, UG, UZ, VN, YU, ZA, ZW (72) Inventor Hollis, Paul             Australia Victoria, North             Ringwood, Harris Road 22 (72) Inventor Dikik, Nebosya             Australia Victoria, North             Melbourne, Oceanashe Street               3/70 (72) Inventor De Nicolo, David             Australia Victoria, West               Essendon, Hampton Road             3/27 (72) Inventor Teril, Stephen             Flemy, Stockholm, Sweden             Ngugatan 45, 4T, Hama             Char (72) Inventor Groves, Christian             Keira, Victoria, Australia             ー 、 Garden Avenue 21 (72) Inventor Ramstrom, Sune             Sweden Sandsball, Capte             Sugatan 11 (72) Inventor Ritchina, Ian             Got, Stockholm, Sweden             Landsgatan 58, Estea             Le, Lund (72) Inventor Cali, Lars             Hellen, Stockholm, Sweden             Borgsgatan 8 Sea (72) Inventor Noguera Rodriguez, Juan             Australia, Victoria, Essen             Don, Deakin Street 3/48 (72) Inventor Dingle, Barry             Minkala, Croydon, Australia               Coat 12 F-term (reference) 5K051 AA03 CC01 CC02 CC07 DD01                       GG02 HH03 HH19 JJ05 JJ14

Claims (36)

[Claims] 1. A method of negotiating a call function between signaling points in a telecommunications system, wherein a feature preference or prioritized preference list is sent at a call control level from an originating signaling point to a terminating signaling point or signaling transfer point. And, if the terminating signaling point or signaling transfer point accepts the preferences sent by the originating signaling point, returning a capability acceptance at the call control level from the terminating signaling point or signaling transfer point to the originating signaling point, A method comprising: 2. The method of claim 1, wherein if the terminating signaling point or signaling transfer point does not accept either the feature preference or the preference list sent by the originating signaling point, an acceptance message is returned. No, in which case the default feature is assumed by both points. 3. Method according to claim 1 or 2, characterized in that the negotiating function relates to a speech codec. 4. Method according to claim 1 or 2, characterized in that the negotiating function relates to security. 5. A method as claimed in any one of the preceding claims, characterized in that the protocol used to perform the negotiation is a call control protocol. 6. The method according to any one of the preceding claims, wherein the paging control level and the bearer control level are controlled by different protocols, and if the selection affects the bearer level, the signaling point is the bearer control level. And responding to the selection of a function at the call control level by notifying the. 7. The method according to any of the preceding claims, characterized in that the signaling point or signaling transfer point is a media gateway controller communicating with one or more media gateways at bearer control level. how to. 8. A method as claimed in any one of the preceding claims, wherein the paging control level negotiates with the bearer control level when a feature preference or prioritized preference list is received at the terminating signaling point or signaling transfer point. A method of performing to determine option availability at a bearer control level. 9. A method according to claim 8 when dependent on claim 7,
The method according to claim 1, wherein the negotiation is performed between a paging control level media gateway controller and a bearer control level media gateway. 10. The method of claim 9, wherein when the prioritized preference list is sent from the originating signaling point to the media gateway controller, the controller modifies the list to support the corresponding media gateway. It deletes the preferences that it knows are not present and sends the modified list to the Media Gateway, which selects the highest priority preference that the Media Gateway can currently support, and the Gateway secures the resources it needs. , A method of notifying a media gateway controller of preferences. 11. A signaling point arranged to negotiate a paging function with another signaling point in a telecommunications system, wherein a paging list of function preferences or prioritized preference is provided to a terminating signaling point or signaling transfer point. And a means for receiving at the call control level from the terminating signaling point or signaling transfer point the capability acceptance sent if the terminating signaling point or signaling transfer point accepts the preferences sent by the originating signaling point. And a signaling point comprising: 12. A media gateway controller for a telecommunications system, means for receiving, from a peer media gateway controller, a functional or prioritized preference list for connections set up through the telecommunications system, and a media gateway controller. Means for communicating with a corresponding media gateway to determine the availability of the preference content received by the media gateway, and means for returning a function preference acceptance message to the peer media gateway controller according to the availability determined by the media gateway. A media gateway controller characterized by comprising. 13. A media gateway for a telecommunications system, means for receiving from a media gateway controller a feature preference or prioritized preference list for a connection set up through the telecommunications system, and a preference content of the media gateway. A media gateway comprising: means for selecting a preference content according to availability; and means for transmitting the selected preference content to the media gateway controller. 14. A method for negotiating protocol options between first, second, and third nodes in a telecommunications network that uses separate call control protocols and bearer control protocols, the first node comprising: A first call control message specifying a protocol option supported by the first node to the second node, and a second specifying a protocol option supported by both the first and second nodes. Sending a paging control message from the second node to the third node, and selecting a protocol option from the protocol options specified in the second control message. 15. The method of claim 14, wherein the step of selecting a protocol option from protocol options specified in the second control message is performed at a third node. . 16. The method of claim 14 or 15, wherein each call control message includes a preference level corresponding to each specified protocol option. 17. The method according to claim 14, wherein the first node is a source node. 18. A method according to any of claims 14 to 17, characterized in that the third node is a terminal node. 19. A method according to any of claims 14-18, wherein it is determined whether the bearer level between a first node and a second node is affected by the selecting step. The method further comprising performing an action to modify bearer level parameters between the first node and the second node if the bearer level is affected. 20. The method according to any of claims 14 to 19, wherein it is determined whether the bearer level between the second node and the third node is affected by the selecting step, If the bearer level is affected, the method further comprises performing an action of modifying a bearer level parameter between the second node and the third node. 21. A method for setting up a call paging connection in a telecommunications system wherein a paging control protocol is transport mechanism independent, the method comprising: a first signaling point between an originating signaling point and a first terminating signaling point of the system. The call codec of the first call signaling point, and the step of establishing a paging connection between the originating signaling point and the first terminating signaling point via a transport mechanism according to the first call codec. Then, between the terminating signaling point and the second new terminating signaling point, negotiating a second different call codec, notifying the originating signaling point of the second call codec, and an originating signaling point. Establishing a paging connection between the second calling signaling point and the second terminating signaling point, the first originating signaling point acting as an intermediate signaling point, and the first paging connection being the second call codec. A step of being modified as necessary to support the method. 22. The method according to claim 21, wherein the first call connection is modified so that a transport connection between an original termination signaling point and a new termination signaling point is later modified according to a new codec. A method comprising the step of establishing. 23. The method according to claim 21 or 22, wherein the appropriate call control (CC) from the original terminating signaling point to the originating signaling point.
Informing the originating signaling point of the second call codec by sending a message. 24. The method of claim 23, wherein the call control protocol is a Transport Independent Call Control (TICC) protocol and the CC message is a "Modify.Request" message. 25. A telecommunications system in which a call control protocol is transport mechanism independent, and means for negotiating a first call codec between an originating signaling point and a first terminating signaling point of the system. And means for establishing a paging connection via a transport mechanism between an originating signaling point and the first terminating signaling point according to the first call codec, the first terminating signaling point and the second terminating signaling point. Means for later negotiating a second different call codec with the new terminating signaling point, means for notifying the originating signaling point of the second call codec, originating signaling point and said second terminating signaling Make a call connection with the point The first outgoing signaling point acts as an intermediate signaling point, and the first paging connection is modified as necessary to support the second call codec. A system characterized by that. 26. A signaling point of a telecommunications network, the call control protocol of which is independent of a transport mechanism, the processing means for negotiating a first end signaling point and a first call codec; Means for establishing a paging connection between a calling signaling point and the first terminating signaling point via a transport mechanism according to a call codec; and the first terminating signaling point and the second new terminating signaling point. Means for receiving a notification of the second call codec negotiated between the two, and means for modifying the first call connection as needed to support the second call codec. Signaling point to be. 27. A method of setting up a call connection between first and second mobile telephone networks, either network being tandem free operations (TFO) installed outside a radio access network portion of the mobile network. A device, wherein the call control protocol is independent of the bearer transport mechanism, wherein the TFO device of one mobile network and the peer TFO device of the other mobile network are used to determine the appropriate call codec. Between the two TFO devices, and sending a call control (CC) message from the corresponding TFO device to notify the radio access network of the determined call codec. Method. 28. The method of claim 27, wherein each mobile network includes a tandem free operations (TFO) device outside a radio access network portion of the mobile network. 29. The method according to claim 27 or 28, characterized in that the two mobile telephone networks are linked to each other via the PSTN. 30. The method according to any of claims 27 to 29, wherein the negotiation uses a codec mismatch resolution and optimization procedure of the TFO protocol, the TFO message using in-band signaling. And then send. 31. The method according to any one of claims 27 to 30, wherein the or each TFO device installed outside a radio access network provides a gateway MSC (providing an interface between a mobile network and an external network). GMSC). 32. The method according to any one of claims 27 to 31, wherein the network installed by the tandem free operation (TFO) device outside the radio access network part is a Universal Mobile Telecommunications System (UMTS) network. And the radio access network is a UMTS terminal terrestrial radio access network. 33. A device for setting up a call connection between first and second mobile telephone networks, at least one of which is located outside the radio access network part of the mobile network, in tandem free operation (TFO). ) A device whose call control protocol is independent of the bearer transport mechanism, said TFO device of one mobile network and a peer TFO device of the other mobile network in order to determine the appropriate call codec. And a means for notifying the radio access network of the determined call codec by transmitting a call control (CC) message from the corresponding TFO device. Device to do. 34. A method of setting up a paging connection between a first and a second mobile telephone network, each network comprising tandem free operations located outside a radio access network portion of the mobile network.
TFO) device, the call control protocol is independent of the bearer transport mechanism, and both mobile networks are connected via the public switched telephone network (PSTN) to determine the appropriate call codec. In order to carry out a negotiation between two mobile terminals respectively subscribed to the first and second mobile networks, the negotiation being exchanged between the radio access network part and each TFO device. Performing using a call control protocol signaling message and an ISUP message sent between TFO devices. 35. The method of claim 34, wherein a list of codecs available on an originating mobile network is transmitted from a TFO device of the network to a peer TFO device using an ISUP Initial Address Message (IAM). , Sending the selected codec back to the originating network in a subsequent ISUP message. 36. A device for setting up a paging connection between first and second mobile telephone networks, each network being tandem free operation located outside the radio access network part of the mobile network.
TFO) device, the call control protocol is independent of the bearer transport mechanism, and both mobile networks are connected via the public switched telephone network (PSTN) to determine the appropriate call codec. Means for performing a negotiation between two mobile terminals respectively subscribed to the first and second mobile networks, the negotiation comprising a radio access network part and each T
Call control protocol signaling messages and TFs exchanged between FO devices
O means for performing using ISUP messages transmitted between devices.