SE516306C2 - Internet protocol based telephone system in which telephone traffic is transmitted at least in part over an Internet protocol based network retaining terminal telephones and exchanges - Google Patents

Abstract

Subscribers (10,20) are respectively connected to access nodes (11,21) connected to a computer or Internet protocol (IP) based packet switching network (30), I.e. the Internet, while telephony servers (40,50) control establishment of calls to and from the subscribers. A telephony number server (60) is a database containing lookup tables for converting a telephone number identifying a subscriber into an IP address or address of the telephone server. Signaling between the subscribers and exchanges is carried out using a V5.1 protocol for public switched telephone networks and integrated services digital network (ISDN) base rate interface for ISDN primary rate interfaces. The standard user to network protocol is overlaid on an IP based network protocol. Independent claims are included for a method of establishing telephone calls between subscribers, for telecommunication means, for an access link and for a telephone exchange.

Description

516,306 o v; u o u v vn 2 connected infrastructure, there is still a need to maintain as much as possible of the wired system.

THE INVENTION IN BRIEF The invention provides a hybrid arrangement which allows an existing wired telephone network to be used for a data packet-switched network. In essence, the underlying wired transport network is replaced by that of an IP-based data packet-connected network, while the wired infrastructure, such as terminals, telephone exchanges and the like, is maintained with modifications. In preferred embodiments of the invention, both a subscriber and a local telephone exchange are connected to, and separated by, a data network. The signaling between the subscriber and the exchange is performed using standard user / network protocol1, such as V5.1 for PSTN and ISDN basic frequency interface (BRI) or DSS1 for ISDN primary fi equivalent interface (PRI). This standard user / network protocol is superimposed on an IP-based network protocol, such as TCP or UDP. By utilizing protocols that are conventionally used by the corresponding circuit switching system elements, the transition from wired to IP-based data packet-switched network transport can be achieved in a fast and secure way because the network elements are interchangeable with different suppliers' equipment. Furthermore, the existing services, which are supported by the standard protocol, will be supported in the data packet-switched network.

In addition, the connection of the subscriber, or the access node to which a subscriber is connected, to the IP-based network enables the full future use of the IP-based network without extensive modification of the system.

BRIEF DESCRIPTION OF THE DRAWINGS Additional objects and advantages of the present invention will become apparent from the following description of preferred embodiments, given by way of example with reference to the accompanying drawings, in which: l schematically shows a telecommunication network according to the present invention, fi g. 2 shows an arrangement for a telephone server, fi g. 3 shows an access node according to the present invention and fig. 4 shows the signaling between the different elements in the network according to fi g. 1, fi g. 5 shows the interaction between the network according to fi g. l and a nearby data packet-connected network, fi g. 6 shows a first embodiment of a network element adapted to interact with adjacent networks, fi g. 7 shows a second embodiment of a network element adapted to interact with adjacent networks and fi g. 8 shows a third embodiment of a network element adapted to interact with adjacent networks.

DETAILED DESCRIPTION OF THE DRAWINGS Fig. 1 shows a hybrid network according to the present invention, where a call is in progress between an A-subscriber 10, represented by the telephone A to the left of the clock, and a B-subscriber 20 shown to the right of the clock. The subscribers are each connected to an access node 11, 21 and these access nodes 11, 21 are in turn connected to a data or similar IP-based data packet-connected network 30, which is typically the Internet.

Connected to the data network 30 is also a telephony server 40, which constitutes the host server for the subscriber A 10 and controls the connection of calls to and from the subscriber A 10, and a similar host telephony server 50 for the subscriber B 20. The telephony servers 40, 20 25 30 516 306 4 50 are AX switches with modifications as described below with reference to fi g. 2. They perform the equivalent role of a local exchange or terminus in a standard wired telephony system, with the essential difference that they use the IP-based data packet network as an exchange. Each telephony server 40, 50 can also handle wired exchange calls and thus cooperate with a traditional wired network, as illustrated with the illustrated interface in the telephone server 40 to a wired access network 80 and the interface in the telephone server 50 to a wired ssv network 90. Also a telephone number server 60 is connected to the data network 30. The telephone number server 60 is essentially a database containing reference tables for converting telephone numbers identifying a subscriber to an IP address or addresses: for the host telephony server 40, 50 for the subscriber, to which the call must be connected. It has been implemented on a standard UNIX DNS server with BIND software using standard DNS record types, which converts e.164 numbers into IP addresses for telephone server endpoints in the network. Consequently, the input signal to the reference table is an e. 164 destination (B-number) or part of this number. The output signal may be an IP address or addresses indicating the host telephony server for the subscriber in question.

The telephone number server 60 contains only addresses of the subscribers who connected to its own network 30. The IP addresses are defined in advance and each subscriber or each physical access to the IP network is assigned an address. The IP address preferably identifies a UDP port, which may be a fixed relationship to a time slot it uses. For some UDP ports, the routing information included in an IP data packet may include the UDP port and the IP address of the port. A number of telephony resource devices 70 are also connected to the data network in different positions.

These are general telephony resources used by a telephony server 40, 50 to support a call. Typical resources include, but are not limited to, answering machines, conference call devices, tone transmitters / receivers, tone detectors, voice message systems, and echo cancellers. It is advantageous that these resources are centrally located in the data network 30 rather than being coordinated with a telephone server. This would significantly increase their level of utilization and make them more cost-effective. However, since the telephony resources of the above kind are already available in a conventional AX exchange, these resources are retained in the telephony server 40 in the preferred embodiment according to fi g. 1.

Fig. 2 shows a schematic representation of a telephony server 40. The elements of the telephony server 40 comprise conventional connection hardware 41 for securing lead-connected connections in the connected wired network. A number of terminals 42 are connected to the switching hardware and normally include a T1 transmission service terminal and an E1 transmission service terminal. Each terminal is connected to an associated wired network, in fi g. 2 represented by the network 80. The switching hardware 41 is further connected to an intermediate measuring line 43, which comprises a PCM / IP adapter for converting a PCM-encoded 64 kbps channel into IP data packets for transmission via the IP-based network. And vice versa. The PCM / IP converter 43 packs substantially 64 kbps bitstream for transmission over the data network 30 in IP-compatible data packets or datagrams and similarly unpacks data packets arriving at the telephony server 40. Furthermore, an IP connection controller 44 is provided. to secure the virtual connection formed by the data network 30 for calls utilizing the data network. The IP connection controller 44 has essentially one. logical view of the IP network 30 such as an electron switch with the input and output points on the switch constituting the various media intermediate network lines from the telephone server 40, such as the intermediate network line 43, and the subscriber access nodes 1 1, 12. The IP switching controller 44 needs access to hardware in order to be able to communicate with and control the various media intermediate measurement lines, but it does not need to include any hardware per se but rather the same IP network hardware interface as the intermediate network line 43. The telephony server further comprises a controller 45 for controlling the switching function of the various elements 41, 43, 44. The controller 45 also handles call connection and sends the required messages according to the agreed user / network protocol, for example V5 .x or DSS1, to the subscribers 10 which are managed by the server 40. The controller 45 includes a routing function for handling all types of call transmission paths, ie. calls that are completely transmitted within the wired network, calls that are transmitted between the wired network and the data network and calls that are transmitted within the data network.

As mentioned earlier, a number of telephony resources are available in the conventional AX exchange. These are represented in the telephony server 40 by block 46. The allocation of these resources for a call is controlled by the controller 45. The resources are then forwarded to the call via the switching hardware 41 or wired transmission paths or the midline 43 if the call includes a subscriber to the packet-switched network 30.

The various elements of the telephony server 40, represented by the hardware 41 and the terminals 42, are needed only to enable a voice path to be routed through the telephony server to a wired network. If the call is connected between two subscribers 10, 20 who are connected to the IP network, these elements will not be part of the communication. The interconnect line 43 is also used for interconnection calls, but it may also be required to generate a voice path when the telephony resources 46 are located as illustrated in the telephony server 40. Thus, those skilled in the art will recognize that these elements need not be part of a telephony server an interface to a wired network and which does not include any telephony resources- SGI.

The network further includes a TNS resolver 46 for managing the interface between the telephone server 40 and the telephone number server 60. It establishes a connection with the telephone number server 60 when the telephone number server 60 is to be activated. Preferably, it will also handle the administration of the IP addresses of the telephone number server 60 such as defining new numbers and updating the telephone number server 60 when subscribers are connected or disconnected. Although the administration functions of the TNS resolver 46 are included in the telephony server 40, those skilled in the art will recognize that a separate network administration node remote from the telephony server 40 could perform this function. 20 25 30 7 The access node 11 is shown in fi g. 3. A number of subscribers A, C and D are connected to the access node 11. The subscribers gain access to this node ll in the traditional wired way, i.e. via a two-wire PSTN terminal for the subscriber A, an ISDN BA ( basic rate access, 2B + D) terminal for the subscriber C or an ISDN PRA (primary rate access, 3OB + D) terminal for the subscriber D, which has been illustrated as a PABX. The PSTN and ISDN BA terminals are connected to a signaling function 12, which essentially performs the task of a conventional V5.x access node. In this function 12, the signaling is collected to or from the two-wire subscriber and transmitted into or out of a 64 kbps signaling channel with 2 Mbps pulse code modulation (PCM). A PCM / IP converter 13 is connected to this signaling function 12 and packs the 64 kbps channel into IP data packets and directs these data packets to the correct destination in the IP network. This routing is performed under the control of the telephony server 40. The PCM / IP converter also performs the reverse conversion and unpacks the IP data packets into a 64 kbps bitstream. The primary frequency access (PRA) interface is likewise provided with a PCM / IP converter 14 which performs a similar function. Although these transducers 13, 14 are depicted as separate units in fi g. 3, those skilled in the art will recognize that the same functional blocks can perform packing, unpacking, and routing functions for both interfaces.

The different forms of signaling that occur between the different elements over the data network 30 are summarized in the diagram according to fi g. 4. All protocols are carried by IP. The superimposed protocols are preferably "standard" or commonly used protocols that allow network elements to be exchanged for equipment olika 'of different makes.

The so-called standard protocols are preferably well-established ITU protocols, which are easily understood by the wired network elements connected to the opposite side. This also allows the maintenance of the various procedures supported by commonly used protocols. Consequently, the signaling between the access node ll and the telephony server 40 during call connection and for communicating routing information to the access node ll outputs a trace protocol A] such as V5.x or the like over UDP. For ISDN primary fi e-equal access, DSS1 is used over UDP. A connection protocol B] is also provided and can normally be V5.x BCC over TCP. Communication between two telephony servers connected to the IP-based network utilizes a traction protocol D], which is normally an SS7 ISUP over TCP. A connection protocol E] is also provided, which may be part of ISUP or outside ISUP. The telephony servers 40, 50 communicate with the telephone number server 60 for requesting the destination IP address associated with a particular b-number using an appropriate protocol C], which is preferably a DNS protocol over TCP. Finally, two additional protocols are provided for communication between a telephony server 40, 50 and the telephony resources 70.

These include a protocol F] for occupancy and control resources as well as the F ”] connection part of F]. and F °] do not have to be standard protocols because the telephony resource nodes 70 are completely new elements that have no equivalent in a wired system. IETF protocol was used for the current data packet transport.

The same applies to lower address resolutions and new network elements.

Before calls are allowed over the access node II, a signaling channel must be established between the signaling function part 12 of this access node II or PABX and the host telephony server 40. This means the establishment of a LAPV5 and an LAPD data layer, respectively. An administrative procedure initiates an order from the telephony server 40 to the PCM / IP converter 13, 14 in question to start sending or receiving IP data packets that * contain information fi- from the 64 kbps signaling channel in the 30B + D or V5.x interface. The PCM / IP converter 13, “14 treats this signaling channel as a pure 64 kbps bitstream, but it can clog the LAPV5 or LAPD frame format and transmit these frames as UDP / IP data packets. Obviously, the same handling of the signaling channel must be performed on both sides of the link. The PCM / IP converter in the intermediate measuring line 41 of the telephony server 40 thus operates in the same way as the converter 13, 14 of the access node 11. The signaling to and from the telephony server 40 can then be transparent to the PCM / IP converters 13, 14.

When a call is to be connected or disconnected, the PCM / IP converter 13, 14 receives additional commands from the host telephony server 40 for establishing or releasing paths. Creating a path means directing the agreed 64 kbps bitstream between the telephony server 40 and the PABX or signaling function 12, packing it in UDP / IP data packets or unpacking it from UDP / IP data packets, and directing them to the destination specified by the telephony server 40.

If the telephony resources 70 are to be used in a call initiated by subscriber A to subscriber B, then these resources must first be occupied by the host telephony server 40 using protocol F] as described above. Thereafter, the resource function shall be routed through the access network II which connects the calling subscriber A. Thus, if a tone transmitter has been assigned as a resource, the 'tone' data packet shall be sent from the telephony resource node 70 to the subscriber A, while voice data packets are exchanged between the subscribers A and B during a conversation.

In the case illustrated in fi g. 1, where telephone resources are available as part of the telephone server 40, a 'voice path' must initially be established between the access node 11 for the subscriber and the telephone server 40 when the call is connected to digital reception to enable the telephone resources to be made available for the call. This is indicated by the dashed line between the telephony server 40 and the access node ll i fi g. A similar path shall be connected for voice data packets if subscriber A is to connect or receive a call to or from a subscriber connected to the wired access network 80. I fi g. 1, the UDP / IP voice data packets exchanged between the subscriber A and the subscriber B are indicated in a similar manner by a dashed line over the data packet-switched network 30.

As stated above with reference to fi g. 1, the telephone number server 60 contains only address information for endpoints within the network to which it is connected. If a call is routed to a subscriber connected to adjacent networks, the telephone number server 60 in the network 30 will have no destination address. F i g. 5 illustrates the situation when calls cross two separate IP-based data packet-switched networks, network A and network B. I fi g. 5, the elements of the network B are considered to be similar to those of the network A and have been denoted by the same reference numerals modified with a prime character. I 20 25 30 516 306 10 fi g. 5, IP network boundary intermediate network lines 61, 61 'are connected to each data network 30, 30 ". These intermediate measuring lines 61, 61 ° may be separate elements in the network or they may form part of the associated telephony server 40, 40 ”. The network boundary intermediate network lines 61, 61 'handle communication between different IP-based networks or IP between IP-based networks operated by different operators. The way in which this is done depends on how the operators of adjacent networks agree to cooperate.

According to a first embodiment of the present invention, each telephone number server 60, 60 'in a first network 30 holds the addresses of network boundary intermediate measurement lines 61, 61' to nearby networks. When a call fi from the network A is destined for the network B, the telephone number server 60 in the network A will provide the telephony server 40 in the network A with the IP addresses of the network boundary intermediate line 61 'to the requested end or transit network, in this case network B. comes to the landline network via the connection point between networks A and B, the landline network intermediate line 61 'will request that its telephone number server 60' determine where to end the call. A call between the networks thus produces two calls to the telephone number servers 60, 60 ', namely a call from the telephone server 40 to the telephone number server 60 in the network A and a call from the network boundary intermediate measuring line 61' to the telephone number server 60 "in the network B.

In a second embodiment according to the present invention, the telephone number server 40 in a network does not contain the addresses of the network boundary intermediate network lines 61 ° in remote networks but instead holds the addresses of the network boundary intermediate network lines 61 in its own network. The telephone number server 60 thus contains only the addresses of real endpoints in its own network. The network grass intermediate network 61 then stores the addresses of adjacent network intermediate interfaces entered by the operators of these networks. All calls between adjacent networks would then be forced to go via these network boundary intermediate lines.

Figs. 6 - 8 show examples of network boundary intermediate network lines 61, 61 'which operate in accordance with the latter embodiment. In these embodiments, the network boundary intermediate network lines 61, 61 'are separated from the telephony servers 40, 40' and are intended for both incoming and outgoing calls. Similar parts have been indicated by the same reference numerals in these three fi gures.

Fig. 6 shows two network boundary intermediate measuring lines 61, 61 ”NGB1 and NGB2, which are interconnected with a wired interface. A first network boundary intermediate measuring line 61 belongs to the network A owned by a first operator. The second network boundary intermediate measuring line 61 'belongs to a network owned by a second operator. The boundary between the two IP-based networks A and B is illustrated by the dashed line. Each network boundary intermediate network line 61, 61 "comprises a signaling intermediate network line SG1 611, SG2 611 'for the exchange of standard telephony protocol messages and a switching signaling protocol CONSIG as well as a message intermediate network line MG1 612, MG2 612' for the exchange of voice data. The transition from an IP-based format to a wired format increases the delay of the speech stream, but the interface is relatively easy to monitor with respect to statistical functions and control or the like. The interface between the network interfaces 61, 61 'is a standard telephony interface, such as ISUP over El. The signaling intermediate measuring line 1 SG1 receives an address for speech from the local telephony server 40 consisting of an IP address and UDP port in the CONSIG protocol. This address points to the A-subscriber side and is used by MG1 to route the speech IP packet, which originates in the subscriber B and is received via a time slot on the wired interface, to the subscriber A. The address of the speech j stream, which has its Originally given to the subscriber A, the subscriber B generates an NGB2 61 ° of the network boundary intermediate network line after it has queried its local telephone number server. It is sent to NGB1 61 by the signaling intermediate measurement line SG2 via the CONSIG protocol. The voice stream from A to B was sent from Ai data packets with a destination address for MG 1. MG1 unpacks the speech stream and inserts it into a time slot. MG2 repackages the speech stream in IP data packets with the destination address for B.

The reverse process takes place for the voice stream fi from B to A. In this embodiment, the IP / UDP addresses of the two networks do not need to be coordinated. The network boundary intermediate measuring lines NGB1 and NGB2 only need to be associated via CIC time slots per call basis. .20 25 30 516 306 12 In the embodiment shown in fi g. 7, the voice stream passes via the IP network as illustrated with the network by connected routers R. The network boundary intermediate network lines 61, 61 ”thus do not comprise any message intermediate measuring line but have only one signaling intermediate network line SG 611. As with the previous embodiment, the signaling intermediate 6 'ISUP / TCP messages and CONSIG / TCP messages (both over IP) with elements within their own networks. However, these messages are also exchanged at the interface between the network interface intermediate measurement lines 61, 61 *, which is an IP-based interface. The CONSIG protocol is not completed. The CONSIG protocol transports the addresses of A to B and B to A. The speech data packets are transmitted directly through the IP-based network without control of the network boundary intermediate measuring lines 61, 61 ”.

However, the interface between the two adjacent networks A and B is designed so that all numbers between operator measurements always go between an assigned pair or an assigned group of conductors. This is illustrated by the solid lines between the conductors R representing possible paths. In this way, measurement and monitoring functions can still be performed in these assigned conductors.

In the third embodiment shown in fi g. 8, the arrangement of the network boundary intermediate network lines 61, 61 ”is very similar to that shown in fi g. 7 with the exception that the operators of networks A and B can not impose any physical restrictions with regard to the path that the voice train will take within the network. The IP-based network can also be owned by a separate operator. In order for the operators of the network where the call originates and where it ends, to curb the speech trajectory to pass a certain point in the IP network, for example for enabling measurement, a routing control function has been introduced in the network boundary intermediate lines 61, 61 '. The conductor may be outside the grid boundary measuring lines 61. 61 * as shown in fi g. 8 or be integrated with the network boundary intermediate network lines 61, 61 'in the manner applicable to the message intermediate network line 612 according to fi g. The signaling interconnect line 611 will then not only bypass the endpoint addresses in the CONSIG protocol. Instead, an address received by the signaling intermediate measurement line 611 will be transmitted to. a new address sent (as a representative) and a control interface, illustrated by a thick line in fi g. 8, and protocol G5 will command a router to feed a speech stream, which arrives at an interface, to be routed out through an armored interface.

The arrangement of the telephone number server 60 essentially produces a plan, non-hierarchical structure, where neither the IP addresses nor the e. 164 numbering plan need be coordinated with other network administration administrations. The only coordination needed refers to the intercoordination points or network boundary intermediate measurement lines 6 to other networks. This structure thus utilizes the advantages of IP connection and with the more well-structured e. 164 numbering plan, where each network administrator has greater freedom in denying the numbering.

The arrangements described above provide a means of bringing an IP-based network closer to the subscriber by replacing the underlying wired transport network with an IP-based data packet-switched network while maintaining costly elements in a circuit-switched network.

Claims (22)

20 25 30 - 516 506. . - ø. .a 14 Patent claims A method of connecting a telephone call between a subscriber and an additional party, characterized in that the subscriber of a data network (30) is separated from a telephone exchange (40) for controlling telephone lines to and from the subscriber, the method comprising : formation of messages using user / network protocol (Aj, B]) for connection of a telephone call, and exchange of these messages between the subscriber and the telephone exchange in an IP-based network protocol format over said data network (30). Method according to claim 1, characterized in that the subscriber is provided with routing information indicating the address of the further party and in that a voice connection is connected at least in part over the data network between the subscriber and the further party. Method according to claim 1 or 2, characterized by the use of the telephone exchange (40), interrogation of a converter device (60) to obtain the address of the further party. Method according to claim 3, characterized in that the converter device (60, 60 °) provides the address of a terminal device (61, 61 ") in a nearby network (30 ') when the further party is not directly or indirectly connected to the data network (3). O). Method according to claim 3, characterized in that the converter device (60, 60 ') provides the address of a terminal device (61) in the same network as the converter device, which method further comprises interrogating the terminal device to obtain the address of the further party. 20 25 30 5 '| 6 31365 15 - | u ~. n » A method according to any one of the preceding claims, characterized by providing telephony resources (45, 70) connected to the data network (30), the method further comprising: coating said telephony resources (70) and establishing a transmission path between the telephony resources and the subscriber. Method according to claim 6, characterized in that the transmission path is a voice path which uses an IP-based network protocol format. Method according to one of the preceding claims, characterized in that the data network (30) is the Internet. A telecommunication system comprising at least one voice tracker subscriber and a telephone exchange (40, 50) for controlling telephony traffic to and from the subscriber, characterized in that a data network (30) is interposed between the subscriber and the telephone exchange (40, 50) and means ( 13, 14, 43) are arranged at the subscriber and the telephone exchange (40, 50) for converting the messages in a user / network protocol format (A], B]) into an IP-based network protocol format for transmission between the subscriber and the telephone exchange (40, so) Telecommunication system according to claim 9, characterized in that the telephone exchange (40, 50) is connected to a PSTN and / or ISDN network (80, 90). Telecommunication system according to claim 9 or 10, characterized in that the user / network protocol is one of a V-series signaling and tracking protocols and DS S 1. Telecommunication system according to one of Claims 9 to 11, characterized by means (60, 60 °) with interfaces to the data network (30) for converting a nununer which identifies a called party into a data network address. 20 25 30 516 306 16 Telecommunication system according to claim 12, characterized by means (47) in the telephone exchange (40) for sending a conversion request to the conversion means (70) using an IP-based network protocol (C]). Telecommunication system according to one of Claims 9 to 13, characterized by means (44) in the telephone exchange for connecting a transmission path between subscribers (10, 11, 20, 21) connected to the data network (30). Telecommunication system according to one of Claims 9 to 14, characterized by a network terminating means (61) for transmitting address information between the parties to a call in adjacent IP-based networks. Telecommunication system according to claim 15, characterized in that the network terminating means (60) is arranged to interrogate conversion means (61) in the network for obtaining routing information regarding a called party when a call from a nearby network (30 ") is routed. to the network terminating means (60). The telecommunication system according to claim 12 or 13, characterized in that the converter means (61) comprises routing information for routing a call to terminating means (60) located in the same IP-based network (30 ") when a called party is outside the network (30). ) connected to the conversion means (61). Telecommunication system according to any one of claims 9 to 17, characterized by means (45, 70) for generating telephony resources comprising means (40, F], F °]) for connecting a voice path between the resource means (70) and a party to a calls that use a user / network protocol in an IP-based protocol formed over the data network (so). Telecommunication system according to claim 18, characterized in that the telephony resource means (70) are located at a distance from the telephone exchange and comprise interface means for the data network (30). 20 516 306 17 Telecommunication system according to claim 18, characterized in that the telephony resource means (45) are located in the telephone exchange. Access link between a voice traffic subscriber and a telephone exchange (40, 50) for controlling traffic to and from the subscriber, characterized in that an IP-based data network (30) is interposed between the subscriber and the exchange, wherein access means (1 l , 21) are arranged to enable the subscriber's access to the IP-based network, which access means comprise: means (13, 14) for converting messages in user / telephone network protocol message format to an IP-based network protocol message format; in means (13, 14) for converting messages received from the telephone exchange in IP-based network protocol message format to user / telephone network protocol message format; and means (13, 14) as an interface to the data network (30) for transmitting and receiving messages between the subscriber and the telephone exchange using the IP-based network protocol. Access link according to claim 21, characterized in that the access means further comprise means (13, 14) for converting voice data into data packets in an IP-based network protocol.