CN107547483B

CN107547483B - Method for accurate fax negotiation and access gateway

Info

Publication number: CN107547483B
Application number: CN201610490309.2A
Authority: CN
Inventors: 吴方瑶
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2016-06-28
Filing date: 2016-06-28
Publication date: 2020-10-09
Anticipated expiration: 2036-06-28
Also published as: CN107547483A

Abstract

The application provides a method for accurate fax negotiation and an access gateway, which are used for the access gateway to obtain fax information of a calling side and a called side before fax negotiation, so that the success rate of the fax negotiation and the fax data transmission is improved. The method provided by the embodiment of the invention comprises the following steps: the method comprises the steps that a calling access gateway obtains calling side fax information, wherein the calling side fax information comprises the media capability of the calling access gateway, the forwarding capability of a calling SBC and the calling network condition; the calling access gateway acquires a called inquiry instruction and generates a calling notification message according to the called inquiry instruction and the fax information of a calling side; the calling access gateway sends the calling notification message to the called access gateway, so that the called access gateway acquires the called side fax information according to the calling notification message; the calling access gateway receives a called notification message sent by the called access gateway, wherein the called notification message comprises called side presence information, and the called side presence information comprises the media capability of the called access gateway, the forwarding capability of the called SBC and the condition of the called network.

Description

Method for accurate fax negotiation and access gateway

Technical Field

The present application relates to the field of facsimile technologies, and in particular, to a method for accurate facsimile negotiation and an access gateway.

Background

With the application and development of Voice over IP (VoIP) fax services carried by an IP network and the convergence of services between operators, it is often necessary to implement fax with fax machines mounted under different operators by using one access device without modifying the configuration.

The IP Fax system is divided into a calling side and a called side as shown in fig. 1, and both the calling side and the called side include a Fax machine (Fax), an access gateway (SBC), and a Session Border Controller (SBC). The access gateway is used for providing a basic narrowband call access function, and a user mounts Fax and registers with the Fax according to information provided by a Public Switched Telephone Network (PSTN). SBCs provide media aggregation and proxy functions. The PSTN is shared by multiple operators. The user under the access gateway starts the fax process after the call is connected with the called party, the access gateway initiates the fax negotiation process after receiving the fax signal tone, then the sender of the fax receives reinvite renegotiation, if the negotiation is successful, the 200OK is responded, the ACK port of the opposite terminal is received, and the training and data transmission of the fax are started.

As shown in fig. 2, after a user a establishes a call with a user B, the user a serves as a receiver of a fax and the user B serves as a sender of the fax. Step 1, establishing a call between a user A and a user B; step 2, the user A detects that the fax sound initiates a T38 protocol to carry out fax negotiation, the user B does not support the T38 protocol, and a 488 response is given back to the user A; and step 3, initiating transparent transmission (G711a) fax negotiation by the user A, and entering a transparent transmission fax process after the fax negotiation is successful.

In the second conventional fax negotiation method, as shown in fig. 3, after a call is established between a user a and a user B, the user a is used as a receiver of a fax, and the user B is used as a sender of the fax. Step 1, establishing a call between a user A and a user B; step 2, the user A is used as a fax receiving party, the user B is used as a fax sending party, and a T38 protocol is initiated to carry out fax negotiation; at step 3, user a initiates a fax T30 negotiation process as the receiving party (since caller SBC does not require first packet learning, packets such as V21 can be sent normally to user B.

However, the existing fax negotiation method has the following disadvantages:

(1) because Fax is deployed in the current network, network intercommunication with multiple operators may be required, but the requirements of different operator networks on the media capability and the forwarding capability of faxes are different, and the configuration of a gateway for the Fax capability is usually only one, and the gateway cannot be adapted to various different opposite-end network elements simultaneously under the scene of not modifying the configuration. For example, the operator network P only supports G711a fax protocol with a coding and packaging time length of ptime 10ms, and does not support returning an error 488 response after a T38 protocol negotiation fails, for example, in the first conventional fax negotiation method, the user B does not support returning a 488 response, and the user B and the user a cannot return a 488 response to the user a after the T38 protocol fax negotiation fails, so the user a cannot initiate a passthrough fax negotiation, and thus the fax negotiation will inevitably fail; the operator network T requires the fax negotiation to carry the x-modem standard; the carrier network V supports the T38 standard and is required to support T38FaxVersion: 0.

(2) Because the access gateways of the existing network Fax are more deployed below the SBC, Fax signaling negotiation is often successful, but because of the forwarding capability (for example, first packet learning is needed), the first data packet of the receiving party does not know which SBC to send to, which causes Fax failure; meanwhile, the SBC deployed on the operator side may also cause that not all fax renegotiate messages can be transmitted transparently due to some configurations (e.g., codec filtering) of the SBC, thereby causing fax data transmission failure.

Disclosure of Invention

The application provides a method for accurate fax negotiation and an access gateway, which are used for the access gateway to obtain fax information of a calling side and a called side before fax negotiation, so that the success rate of the fax negotiation and the fax data transmission is improved.

The first aspect of the present invention provides a method for accurate fax negotiation, including:

after a calling user establishes call connection with a called user, a calling access gateway acquires calling side presence information, wherein the calling side presence information comprises the media capability of the calling access gateway, the forwarding capability of a calling SBC and the calling network condition;

the calling access gateway acquires a called query instruction and generates a calling notification message according to the called query instruction and the calling side fax information;

the calling access gateway sends the calling notification message to a called access gateway, so that the called access gateway acquires called side truth information according to the calling notification message and acquires the calling side truth information;

and the calling access gateway receives a called notification message sent by the called access gateway, wherein the called notification message comprises called side truth information, and the called side truth information comprises the media capability of the called access gateway, the forwarding capability of a called SBC and the condition of a called network.

When a calling user mounted on a calling access gateway and a called user mounted on a called access gateway establish call connection, the calling access gateway acquires calling side fax information, the called access gateway informs the called access gateway of the caller-side fax information through the caller notification message and instructs the called access gateway to collect the called-side fax information, the called access gateway sends the called-side fax information to the caller access gateway through the called notification message, therefore, the called access gateway and the calling access gateway already know the fax information of the calling side and the called side before fax negotiation, so that when one access gateway is interfaced with access gateways deployed under multiple operators, the fax negotiation message containing the appointed encoding and decoding, the packaging time length, the special a line (such as x-modem) and the special fax version information can be flexibly initiated according to the capability of the opposite terminal, so that the success rate of the fax negotiation is improved; in addition, through obtaining the forwarding capability of the SBC by the access gateway, the failure of fax data transmission caused by SBC limitations (for example, SBC needs first packet learning, has codec filtering and network conditions, etc.) in the fax flow can be effectively avoided, and the success rate of fax data transmission is improved.

With reference to the first aspect of the present invention, in a first implementation manner of the first aspect of the present invention, the obtaining, by the calling access gateway, the caller-side presence information includes:

a calling access gateway (SBC) sends a calling subscription message to a calling SBC, wherein the calling subscription message contains a calling identifier, so that the SBC obtains the calling network condition and the forwarding capability related to the calling identifier according to the calling subscription message;

the calling access gateway receives a calling subscription response fed back by the calling SBC, wherein the calling subscription response comprises the forwarding capability of the calling SBC and the calling network condition;

and the calling access gateway acquires the media capability of the calling access gateway, and analyzes the calling subscription response to acquire the forwarding capability of the calling SBC and the calling network condition.

The calling link of the calling user and the called user is one-to-one during fax, so that the call identifier of the call connection is unique, the calling access gateway acquires the call identifier of the call connection, carries the call identifier in the calling subscription message and sends the call identifier to the calling SBC connected with the calling access gateway, the calling SBC can obtain the forwarding capacity related to the call connection according to the call identifier and obtain the current calling network condition, and the calling access gateway can obtain the media capacity of the calling access gateway through internal detection to explain in detail how the calling access gateway acquires the fax information of the calling side, so that the scheme is clearer.

With reference to the first implementation manner of the first aspect of the present invention, in the second implementation manner of the first aspect of the present invention, after the receiving, by the calling access gateway, the called notification message sent by the called access gateway, the method further includes:

and the calling access gateway performs accurate fax negotiation with the called access gateway according to the fax information of the calling side and the fax information of the called side.

With reference to the second embodiment of the first aspect of the present invention, in the third embodiment of the first aspect of the present invention, when the caller SBC needs first packet learning,

after the calling access gateway performs accurate fax negotiation with the called access gateway according to the calling fax information and the called fax information, the method further comprises the following steps:

and after the accurate fax negotiation is completed, the calling access gateway receives a first packet sent by the called access gateway through the calling SBC, and the first packet is used for the calling SBC to learn the first packet.

After the accurate fax negotiation is completed, it is assumed that the T30 fax protocol has been selected, but the calling SBC needs first packet learning, so although the fax protocol is completed, the data packet still causes failure of fax data transmission because the data packet does not know which SBC to send to during fax data transmission, and if the called access gateway sends a first packet to the calling SBC for first packet learning before fax data transmission, then the fax data transmission can be performed smoothly.

With reference to the second implementation manner of the first aspect of the present invention, in a fourth implementation manner of the first aspect of the present invention, the performing, by the calling access gateway, an accurate fax negotiation with the called access gateway according to the fax information of the calling side and the fax information of the called side includes:

the calling access gateway carries out transparent transmission negotiation with the called access gateway according to the calling network condition and the called network condition, and fax signal tones are detected;

and the calling access gateway performs fax negotiation with the called access gateway according to the fax signal tone, the fax information of the calling side and the fax information of the called side.

If the sender sends fax data without knowing the network condition of the receiver, the quality and success rate of the fax can be affected by the conditions of packet loss, jitter, time delay and the like caused by the mismatching of the network condition and the sending rate, then before accurate fax negotiation, transparent transmission negotiation is carried out according to the network condition, fax signal tones are detected, fax negotiation is carried out according to the conditions of the fax signal tones and by combining the factors of forwarding capability, media capability and the like, the rate which is most matched with the network condition can be selected during the fax negotiation, the quality in the process of transmitting the fax data can be improved, and the success rate is further improved.

The second aspect of the present invention provides a method for fax negotiation, including:

after a calling user establishes call connection with a called user, a called access gateway receives a calling notification message sent by the calling access gateway, wherein the calling notification message comprises a called inquiry instruction and calling side fax information, and the calling side fax information comprises the media capability of the calling access gateway, the forwarding capability of a calling SBC and the calling network condition;

the called access gateway obtains the caller-side fax information and the called query instruction according to the caller notification message;

the called access gateway acquires called side real information according to the called query instruction, wherein the called side real information comprises the media capability of the called access gateway, the forwarding capability of a called SBC and the condition of a called network;

and the called access gateway generates a called notification message according to the called side truth-transferring information and sends the called notification message to the calling access gateway.

When a calling subscriber mounted on a calling access gateway and a called subscriber mounted on a called access gateway establish a call connection, the called access gateway receives the calling notification message sent by the calling access gateway to obtain the calling side fax information and the called query instruction, the called side real information is acquired according to the called inquiry instruction, the calling access gateway is informed of the called side real information through the called notice message, therefore, the called access gateway and the calling access gateway already know the fax information of the calling side and the called side before fax negotiation, so that when one access gateway is interfaced with access gateways deployed under multiple operators, the fax negotiation message containing the appointed encoding and decoding, the packaging time length, the special a line (such as x-modem) and the special fax version information can be flexibly initiated according to the capability of the opposite terminal, so that the success rate of the fax negotiation is improved; in addition, through obtaining the forwarding capability of the SBC by the access gateway, the failure of fax data transmission caused by SBC limitations (for example, SBC needs first packet learning, has codec filtering and network conditions, etc.) in the fax flow can be effectively avoided, and the success rate of fax data transmission is improved.

With reference to the second aspect of the present invention, in a first implementation manner of the second aspect of the present invention, the acquiring, by the called access gateway, the called-side presence information according to the called query instruction includes:

the called access gateway sends a called subscription message to a called SBC according to the called query instruction, wherein the called subscription message contains a calling identifier, so that the called SBC obtains a called network condition and forwarding capacity related to the calling identifier according to the called subscription message;

the called access gateway receives a called subscription response fed back by the called SBC, wherein the called subscription response comprises the forwarding capability of the called SBC and the condition of a called network;

and the called access gateway acquires the media capability of the called access gateway according to the called query instruction, and analyzes the called subscription response to acquire the forwarding capability of the called SBC and the condition of the called network.

Because the calling links of the calling user and the called user are one-to-one during fax, the calling identifier of the call connection is unique, the called access gateway obtains the calling identifier of the call connection, carries the calling identifier in the called subscription message and sends the calling identifier to the called SBC connected with the called access gateway, the called SBC can obtain the forwarding capacity related to the call connection according to the calling identifier and obtain the current called network condition, the called access gateway can obtain the media capacity of the called access gateway according to the called query instruction, and the called access gateway can explain in detail how to obtain the called side real information, so that the scheme is clearer.

With reference to the first embodiment of the second aspect of the present invention, in the second embodiment of the second aspect of the present invention, after the called access gateway generates a called notification message according to the called-side presence information and sends the called notification message to the calling access gateway, the method further includes:

and the called access gateway performs accurate fax negotiation with the calling access gateway according to the fax information of the calling side and the fax information of the called side.

With reference to the second aspect of the present invention, in the third embodiment of the second aspect of the present invention, when the caller SBC needs first packet learning,

after the called access gateway performs accurate fax negotiation with the calling access gateway according to the fax information of the calling side and the fax information of the called side, the method further comprises the following steps:

and after the accurate fax negotiation is completed, the called access gateway sends a first packet to the calling access gateway through the calling SBC, and the first packet is used for the calling SBC to learn the first packet.

With reference to the second aspect and the second implementation manner of the second aspect, in a third implementation manner of the second aspect of the present invention, the performing, by the called access gateway, an accurate fax negotiation with the calling access gateway according to the fax information of the calling side and the fax information of the called side includes:

the called access gateway carries out transparent transmission negotiation with the calling access gateway according to the calling network condition and the called network condition, and fax signal tones are detected;

and the called access gateway performs fax negotiation with the calling access gateway according to the fax signal tone, the fax information of the calling side and the fax information of the called side.

A third aspect of the present invention provides a calling access gateway, including:

the system comprises a calling fax information collection module, a calling side fax information collection module and a calling side fax information collection module, wherein the calling side fax information collection module is used for acquiring calling side fax information after a calling user establishes call connection with a called user, and the calling side fax information comprises the media capability of a calling access gateway, the forwarding capability of a calling SBC and the calling network condition;

the calling processing module is used for acquiring a called query instruction and generating a calling notification message according to the called query instruction and the calling side fax information;

the calling transceiving module is used for sending the calling notification message to a called access gateway, so that the called access gateway acquires called side truth information according to the calling notification message and acquires the calling side truth information;

the calling transceiver module is further configured to receive a called notification message sent by the called access gateway, where the called notification message includes the called-side presence information, and the called-side presence information includes the media capability of the called access gateway, the forwarding capability of the called SBC, and the called network status.

When a calling user mounted on a calling access gateway and a called user mounted on a called access gateway establish call connection, a calling fax information collection module acquires calling side fax information, a calling transceiver module informs the called access gateway of the calling side fax information through a calling notification message and instructs the called access gateway to collect called side fax information, and the called access gateway sends the called side fax information to the calling transceiver module through a called notification message, so that the called access gateway and the calling access gateway know the fax information of the calling side and the called side before fax negotiation, and when one access gateway is in butt joint with access gateways deployed under multiple operators, fax negotiation messages containing specified encoding and decoding, packing time length, special a line (such as x-modem) and special fax version information can be flexibly initiated according to the capacity of an opposite end, the success rate of fax negotiation is improved; in addition, through obtaining the forwarding capability of the SBC by the access gateway, the failure of fax data transmission caused by SBC limitations (for example, SBC needs first packet learning, has codec filtering and network conditions, etc.) in the fax flow can be effectively avoided, and the success rate of fax data transmission is improved.

With reference to the third aspect of the present invention, in a first embodiment of the third aspect of the present invention, the calling fax information collecting module includes: a calling media capability collecting unit, a calling forwarding capability collecting unit and a calling network condition collecting unit;

the calling transceiver module is further configured to send a calling subscription message to a calling SBC, where the calling subscription message includes a call identifier, so that the calling SBC obtains a calling network status and forwarding capability related to the call identifier according to the calling subscription message;

the caller transceiver module is further configured to receive, by the caller access gateway, a caller subscription response fed back by the caller SBC, where the caller subscription response includes forwarding capability of the caller SBC and a caller network status;

the calling media capability collecting unit is used for acquiring the media capability of the calling media capability collecting unit;

the caller forwarding capability collecting unit is used for analyzing the caller subscription response to obtain the forwarding capability of the caller SBC;

and the calling network condition collecting unit is used for analyzing the calling subscription response to obtain the calling network condition.

Because the calling links of the calling user and the called user are one-to-one during fax, the calling identification of the call connection is unique, the calling transceiver module acquires the calling identification of the call connection and carries the calling identification in the calling subscription message, sending the call request to a calling SBC connected with a calling access gateway, wherein the calling SBC can obtain the forwarding capability related to the call connection according to the call identifier, and obtain the current calling network status, the calling forwarding capability collecting unit and the calling network status collecting unit obtain the forwarding capability and the calling network status of the calling SBC by analyzing the calling subscription response fed back by the calling SBC, the calling media capability collecting unit can obtain the media capability of the calling media capability collecting unit through internal detection, how the calling fax information collection module acquires the calling fax information is explained in detail, so that the scheme is clearer.

With reference to the first embodiment of the third aspect of the present invention, in the second embodiment of the third aspect of the present invention,

the calling processing module is further configured to perform accurate fax negotiation with the called access gateway according to the calling fax information and the called fax information.

With reference to the second embodiment of the third aspect of the present invention, in the third embodiment of the third aspect of the present invention, when the caller SBC needs first packet learning,

and the calling transceiver module is further configured to receive, through the calling SBC, a first packet sent by the called access gateway after the accurate fax negotiation is completed, where the first packet is used for the calling SBC to learn the first packet.

After the accurate fax negotiation is completed, it is assumed that the T30 fax protocol is selected, but the calling SBC needs to learn the first packet, so that although the fax protocol is completed, the data packet still causes a failure of fax data transmission because the data packet does not know which SBC to send during fax data transmission, and if the called access gateway sends a first packet to the calling SBC for first packet learning before fax data transmission, and the calling transceiver module can also receive the first packet, so that the fax data transmission can be smoothly performed.

With reference to the second embodiment of the third aspect of the present invention, in a fourth embodiment of the third aspect of the present invention,

the calling processing module is also used for carrying out transparent transmission negotiation with the called access gateway according to the calling network condition and the called network condition and detecting fax signal tones;

the calling processing module is further configured to perform fax negotiation with the called access gateway according to the fax signal tone, the fax information of the calling side, and the fax information of the called side.

Before fax negotiation, the calling processing module firstly carries out transparent transmission negotiation according to network conditions and detects fax signal tones, the calling processing module carries out fax negotiation according to the conditions of the fax signal tones by combining factors such as forwarding capability, media capability and the like, and when the fax negotiation is carried out, the speed which is most matched with the network conditions can be selected, so that the quality in the process of fax data transmission can be improved, and the success rate is further improved.

A fourth aspect of the present invention provides a called access gateway, including:

the called transceiving module is used for receiving a calling notification message sent by a calling access gateway after a calling user establishes call connection with a called user, wherein the calling notification message comprises a called inquiry instruction and calling side fax information, and the calling side fax information comprises the media capability of the calling access gateway, the forwarding capability of a calling session controller (SBC) and the calling network condition;

the called processing module is used for obtaining the caller-side fax information and the called query instruction according to the caller notification message;

a called fax information collection module, configured to obtain called-side fax information according to the called query instruction, where the called-side fax information includes a media capability of the called access gateway, a forwarding capability of the called SBC, and a called network status;

the called receiving and sending module is also used for generating a called notification message according to the called side truth-transferring information and sending the called notification message to the calling access gateway.

When a calling user mounted on a calling access gateway and a called user mounted on a called access gateway establish call connection, a called transceiving module receives a calling notification message sent by the calling access gateway, a called processing module obtains calling side fax information and a called query instruction, a called fax information collecting module obtains the called side fax information according to the called query instruction, and a called transceiving module informs the calling access gateway of the called side fax information through the called notification message, so that the called access gateway and the calling access gateway know the fax information of the calling side and the called side before fax negotiation, and when one access gateway is in butt joint with access gateways deployed under multiple operators, fax negotiation messages containing specified encoding and decoding, packing time length, special a-line (such as x-modem) and special fax version information can be flexibly initiated according to the capacity of an opposite terminal, the success rate of fax negotiation is improved; in addition, through obtaining the forwarding capability of the SBC by the access gateway, the failure of fax data transmission caused by SBC limitations (for example, SBC needs first packet learning, has codec filtering and network conditions, etc.) in the fax flow can be effectively avoided, and the success rate of fax data transmission is improved.

With reference to the fourth aspect of the present invention, in the first embodiment of the fourth aspect of the present invention, the called facsimile information collecting module includes: a called media capability collecting unit, a called forwarding capability collecting unit and a called network condition collecting unit;

the called transceiver module is further configured to send a called subscription message to a called SBC according to the called query instruction, where the called subscription message includes a call identifier, so that the called SBC obtains a called network status and forwarding capability related to the call identifier according to the called subscription message;

the called transceiver module is further configured to receive a called subscription response fed back by the called SBC, where the called subscription response includes forwarding capability of the called SBC and a called network status;

the called media capability collecting unit is used for acquiring the media capability of the called media capability according to the called query instruction;

the called forwarding capability collecting unit is used for analyzing the called subscription response to obtain the forwarding capability of the called SBC;

the called network condition collecting unit is used for analyzing the called subscription response to obtain the called network condition.

The called media capability collection unit obtains the media capability of the called SBC and the called network state according to the called query instruction, and describes in detail how the called fax information collection module obtains the called side-transfer true information, so that the scheme is clearer.

In combination with the first embodiment of the fourth aspect of the present invention, in the second embodiment of the fourth aspect of the present invention,

and the called processing module is also used for carrying out accurate fax negotiation with the calling access gateway according to the calling side fax information and the called side fax information.

With reference to the second embodiment of the fourth aspect of the present invention, in the third embodiment of the third aspect of the present invention, when the caller SBC needs first packet learning,

and the called transceiver module is further configured to send a first packet to the caller access gateway through the caller SBC after the accurate fax negotiation is completed, where the first packet is used for the caller SBC to learn the first packet.

After the accurate fax negotiation is completed, it is assumed that the T30 fax protocol is selected, but the calling SBC needs first packet learning, so that although the fax protocol is completed, the data packet still causes failure of fax data transmission because the data packet does not know which SBC to send to during fax data transmission, and if the called transceiver module sends a first packet to the calling SBC for first packet learning before fax data transmission, then the fax data transmission can be performed smoothly.

In combination with the second embodiment of the fourth aspect of the present invention, in the fourth embodiment of the third aspect of the present invention,

the called processing module is also used for carrying out transparent transmission negotiation with the calling access gateway according to the calling network condition and the called network condition and detecting fax signal tones;

and the called processing module is also used for carrying out accurate fax negotiation with the calling access gateway according to the fax signal tone, the fax information of the calling side and the fax information of the called side.

If the sender sends fax data without knowing the network condition of the receiver, the quality and success rate of the fax may be affected by the conditions of packet loss, jitter, time delay and the like caused by the mismatching of the network condition and the sending rate, before accurate fax negotiation, the called processing module performs transparent transmission negotiation according to the network condition to detect the fax signal tone, performs fax negotiation according to the conditions of the fax signal tone and by combining the factors of forwarding capability, media capability and the like, during the fax negotiation, the rate which is most matched with the network condition can be selected, the quality in the process of fax data transmission can be improved, and the success rate is further improved.

Drawings

Fig. 1 is a block diagram of an IP facsimile system provided in the present application;

FIG. 2 is a signaling flow diagram of a prior art fax negotiation method;

FIG. 3 is a signaling flow diagram of another prior art fax negotiation method;

fig. 4 is a schematic structural diagram of an entity apparatus of an access gateway provided in the present application;

FIG. 5 is a signaling flow diagram of a call connection process provided herein;

FIG. 6 is a schematic diagram of one embodiment of a method for accurate fax negotiation as provided herein;

FIG. 7 is a signaling flow diagram of a method of accurate fax negotiation provided by the present application;

fig. 8 is a signaling flowchart of interaction between a caller access gateway and a caller SBC provided in the present application;

FIG. 9 is a schematic diagram of another embodiment of a method for accurate fax negotiation as provided herein;

FIG. 10 is a signaling flow diagram of the precision fax negotiation step provided herein;

fig. 11 is a signaling flowchart of the calling SBC when the calling SBC needs first packet learning according to the present application;

FIG. 12 is a signaling flow diagram for performing fax negotiation according to network conditions according to the present application;

fig. 13 is a schematic structural diagram of a calling access gateway provided in the present application;

fig. 14 is another schematic structural diagram of a calling access gateway provided in the present application;

fig. 15 is a schematic structural diagram of a called access gateway provided in the present application;

fig. 16 is another schematic structural diagram of a called access gateway provided in the present application;

fig. 17 is a schematic diagram of network element connection of a facsimile system provided in the present application.

Detailed Description

The technical solutions in the present application will be described clearly and completely with reference to the accompanying drawings in the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Fig. 1 is a schematic view of an application scenario according to an embodiment of the present invention.

The invention is applied to an IP Fax system, the IP Fax system is divided into a calling side and a called side, and the calling side and the called side comprise a Fax, an access gateway and an SBC. The access gateway is used for providing a basic narrowband call access function, and a user mounts Fax and registers with the Fax according to information provided by the PSTN. SBCs provide media aggregation and proxy functions.

The PSTN is shared by multiple operators, the PSTN provides an analog proprietary channel, the channels are connected via a plurality of telephone switches, when two hosts or router devices need to be connected through the PSTN, the network access sides at two ends must use a Modem (Modem) to implement analog-to-digital and digital-to-analog conversion of signals, and from the perspective of the OSI seven-layer model, the PSTN can be regarded as a simple extension of a physical layer, and does not provide services such as flow control and error control to users. Furthermore, since the PSTN is a circuit-switched approach, a path is set up until released, and its full bandwidth can only be used by devices at both ends of the path, even though there is no data to transfer between them. It can be seen that once a call connection between two Fax-mounted access gateways is established, the call identity is unique.

As shown in fig. 4, the schematic structural diagram of the entity device of the access gateway includes a Digital Signal Processor (DSP) 401, a Fax information collector 402, a transceiving interface 403, a power supply 404, and the like, where the DSP is mainly used to process Fax data, generate various types of messages, and take charge of Fax negotiation and other work in the present invention, the Fax information collector 402 is mainly used to collect Fax information of a calling side and a called side, the transceiving interface 403 is connected to a mounted Fax and connected to an SBC, and the power supply 404 provides power for the DSP.

As shown in fig. 5, assuming that the user a is the calling side, the access gateway mounted by the user a is used as the calling access gateway, the connected SBC is the calling SBC, the devices in the core network are fully transparent, and the process of making a call between the user a and the user B is as follows: the user A is used as a calling initiating invitation message (INVITE), the invention adopts a G729 Protocol in a Session Description Protocol (SDP), or can be other protocols, the user B returns 180 response to the user A to indicate that the ringing is finished, and returns 200OK response to indicate that the ringing is finished, and the user A sends an ACK port to the user B to complete a calling process, and the user A and the user B establish a calling connection.

The following describes a method for accurate fax negotiation in the above system architecture or scenario by using an interactive embodiment between two access gateways.

Referring to fig. 6, an embodiment of a method for accurate fax negotiation according to an embodiment of the present invention includes:

601. after a calling user establishes call connection with a called user, a calling access gateway acquires calling side fax information;

in this embodiment, as described in the system architecture or scenario, after the user a and the user B have established a call connection, the caller access gateway obtains caller-side fax information, where the caller-side fax information includes a media capability of the caller access gateway, a forwarding capability of the caller SBC, and a caller network status, where the media capability of the access gateway is a fax-related capability of the caller access gateway (e.g., whether to support a 488 response or not), and the forwarding capability of the caller SBC (e.g., whether to need first packet learning or not) and the caller network status are obtained from the caller SBC subscription, and this step corresponds to step 1 in the signaling flow chart shown in fig. 7.

602. The calling access gateway acquires a called inquiry instruction and generates a calling notification message according to the called inquiry instruction and the fax information of a calling side;

in this embodiment, the calling access gateway obtains a called query instruction according to the Fax information of the called side, which is known by the calling access gateway as needed, where the called query instruction may be generated by a user operating Fax, or the calling access gateway automatically generates the called query instruction according to the information item of the Fax information of the calling side, so that the called query instruction is used to instruct the called access gateway to collect the Fax information needed by the calling access gateway, and the calling access gateway generates a calling notification message according to the called query instruction and the Fax information of the calling side, where the step corresponds to step 2 in the signaling flow chart shown in fig. 7, and is specifically: the called inquiry instruction and the calling side fax information are combined into a MessageBody in the INFO message, namely the MessageBody in the INFO message is in an xml format, wherein the MessageBody comprises the called inquiry instruction and the calling side fax information, and the INFO message is a calling notification message.

603. The calling access gateway sends the calling notification message to a called access gateway;

in this embodiment, after the calling access gateway generates a calling notification message, the calling notification message is sent to the called access gateway through the established call connection link, this step corresponds to step 3 in the signaling flow chart shown in fig. 7, the calling access gateway sends an INFO message to the called access gateway, and the called access gateway feeds back a 200OK response after the INFO message is sent.

604. The called access gateway receives a calling notification message sent by the calling access gateway, and obtains calling side fax information and a called query instruction according to the calling notification message;

in this embodiment, after receiving the caller notification message sent by the caller access gateway, the called access gateway parses the caller notification message to obtain caller-side fax information and a called query instruction, where this step corresponds to step 4 in the signaling flow chart shown in fig. 7, and after receiving the INFO message (i.e., the caller notification message), the called access gateway may parse the INFO message MessageBody of the INFO message to obtain the caller-side fax information and the called query instruction.

605. The called access gateway acquires the called side fax information according to the called query instruction;

in this embodiment, the called access gateway obtains called-side presence information according to the called query instruction, where the called-side presence information includes a media capability of the called access gateway, a forwarding capability of the called SBC, and a called network status, the media capability of the called access gateway is the media capability of the access gateway itself, and the forwarding capability of the called SBC and the called network status are obtained by subscription from the called SBC, which corresponds to step 5 in the signaling flowchart shown in fig. 7.

606. The called access gateway generates a called notification message according to the called side fax information and sends the called notification message to the calling access gateway;

in this embodiment, the called access gateway generates a called notification message according to the called-side presence information and sends the called notification message to the calling access gateway, where the step corresponds to step 6 in the signaling flow chart shown in fig. 7, specifically: and forming the called side truth information into a MessageBody in an INFO message, wherein the INFO message is a called notification message, the called access gateway sends the INFO message to the calling access gateway, and the calling access gateway feeds back a 200OK response after the INFO message is sent.

607. And the calling access gateway receives a called notification message sent by the called access gateway.

In this embodiment, the calling access gateway receives a called notification message sent by the called access gateway, so that the calling access gateway can obtain called-side presence information according to the called notification message, which corresponds to step 7 in the signaling flowchart shown in fig. 7.

In the embodiment of the invention, a calling access gateway acquires calling side fax information, informs a called access gateway of the calling side fax information through a calling notification message, and instructs the called access gateway to collect the called side fax information, and the called access gateway sends the called side fax information to the calling access gateway through the called notification message, so that the called access gateway and the calling access gateway know the fax information of the calling side and the called side before fax negotiation, and when one access gateway is in butt joint with access gateways deployed under multiple operators, fax negotiation messages containing specified codec, packing duration, special a-line (such as x-modem) and special fax version information can be flexibly initiated according to the capacity of an opposite terminal, thereby improving the success rate of the fax negotiation; in addition, through obtaining the forwarding capability of the SBC by the access gateway, the failure of fax data transmission caused by SBC limitations (for example, SBC needs first packet learning, has codec filtering and network conditions, etc.) in the fax flow can be effectively avoided, and the success rate of fax data transmission is improved.

In the above embodiment, when the caller access gateway acquires the caller-side presence information, since the forwarding capability of the caller SBC and the caller network status need to be obtained from the caller SBC, the caller SBC needs to be interacted with the caller SBC, which is described in detail below.

Optionally, in some embodiments of the present invention, the obtaining, by the calling access gateway, the live information of the calling side includes:

the calling access gateway sends a calling subscription message to the calling SBC, wherein the calling subscription message contains a calling identifier, so that the calling SBC obtains the calling network condition and the forwarding capability related to the calling identifier according to the calling subscription message;

the calling access gateway obtains the media capability of the calling access gateway, and analyzes the calling subscription response to obtain the forwarding capability of the calling SBC and the calling network condition.

In the embodiment of the present invention, as shown in the signaling flow chart shown in fig. 8, after a call connection is established, a subscribe message (i.e., a caller subscribe message) is sent to a caller SBC, and the call connection includes a call identifier of the call connection, after the call SBC receives a 200OK response, the caller SBC queries, according to the caller subscribe message, forwarding capability and a caller network status related to the call identifier, and feeds back the forwarding capability and the caller network status of the caller SBC to the caller SBC through a Notify message (i.e., a caller subscribe response), the caller SBC parses the Notify message to obtain the forwarding capability and the caller network status of the caller SBC, and detects a DSP of a main access gateway to obtain a media capability, so as to describe in detail how the caller access gateway obtains fax information of a caller side, thereby making a scheme clearer.

It should be noted that the difference between the called access gateway obtaining the called-side presence information and the calling access gateway obtaining the calling-side presence information is that the called access gateway subscribes to the called SBC according to the called query instruction, and besides, the basic flow is the same.

The above embodiment describes the acquisition of fax information, which is followed by the start of an accurate fax negotiation, and is explained by an embodiment below.

Referring to fig. 9, an embodiment of a method for accurate fax negotiation according to an embodiment of the present invention includes:

901. after a calling user establishes call connection with a called user, a calling access gateway acquires calling side fax information;

see step 601 for details.

902. The calling access gateway acquires a called inquiry instruction and generates a calling notification message according to the called inquiry instruction and the fax information of a calling side;

see step 602 for details.

903. The calling access gateway sends the calling notification message to a called access gateway;

see step 603 for details.

904. The called access gateway receives a calling notification message sent by the calling access gateway, and obtains calling side fax information and a called query instruction according to the calling notification message;

see step 604 for details.

905. The called access gateway acquires the called side fax information according to the called query instruction;

see step 605 for details.

906. The called access gateway generates a called notification message according to the called side fax information and sends the called notification message to the calling access gateway;

see step 606 for details.

907. A calling access gateway receives a called notification message sent by a called access gateway;

see step 607 for details.

908. And the calling access gateway performs accurate fax negotiation with the called access gateway according to the calling side fax information and the called side fax information.

In this embodiment, since both the calling access gateway and the called access gateway know the fax information of the calling side and the fax information of the called side, the most suitable fax protocol can be selected for fax negotiation, and other configurations are set, this step corresponds to step 8 shown in fig. 7, as shown in fig. 10, which is an example of step 8 in fig. 7, after the calling access gateway knows that the media capability of the called access gateway has a point that it supports the G711a fax protocol with a coding and packing duration of ptime 10ms, the calling access gateway sends an INVITE message to the called access gateway to perform fax negotiation of the protocol (G711a, ptime 10ms) with the called access gateway.

In the embodiment of the invention, after the calling access gateway and the called access gateway know the fax information of the calling side and the called side, the step of accurate fax negotiation is added, so that the whole fax process is more complete.

In the above embodiment, if the T38 protocol is used after the accurate fax negotiation, and the T38 protocol is to decompose the T30 fax signal into the original fax signal and repackage the original fax signal into the T30 message, if the caller SBC needs the first packet to learn again at this time, the first packet of the T30 message cannot be sent to the caller SBC, which will be solved by an embodiment.

Optionally, in some embodiments of the present invention, when the caller SBC needs first packet learning, after the caller access gateway performs accurate fax negotiation with the called access gateway according to the caller-side fax information and the called-side fax information, the method further includes:

after the accurate fax negotiation is completed, the calling access gateway receives a first packet sent by the called access gateway through the calling SBC, and the first packet is used for the calling SBC to learn the first packet.

In the embodiment of the present invention, as shown in fig. 11, after the accurate fax negotiation is completed, a T38 protocol is selected, and the called access gateway learns that the calling SBC needs first packet learning from the forwarding capability of the calling SBC, so that the called access gateway first sends a CNG message to the calling access gateway, and when passing through the calling SBC, the calling SBC performs first packet learning according to the CNG message, so that the T30 message can normally reach the calling SBC in a subsequent fax process.

Optionally, in some embodiments of the present invention, the performing, by the calling access gateway, accurate fax negotiation with the called access gateway according to the calling-side fax information and the called-side fax information includes:

the calling access gateway performs transparent transmission negotiation with the called access gateway according to the calling network condition and the called network condition, and detects fax signal tones;

In the embodiment of the present invention, as shown in fig. 12, if it is shown in the fax information that the party of the calling network condition and the party of the called network condition is poor, the calling access gateway sends an INVITE (G711a vbd) message, that is, performs transparent transmission negotiation with the called access gateway (originally, G729 is used for detecting fax signal tones, but G729 has a high compression ratio and is not beneficial to detecting fax signal tones), and is used for detecting fax signal tones, and the calling access gateway and the called access gateway initiate T38fax negotiation according to the fax information of the calling side and the called side in combination with the fax signal tones, because the T38 protocol is low-speed fax, when packet loss occurs due to poor network condition, the fault tolerance rate of low-speed fax to packet loss is good.

The above embodiment describes the method for accurate fax negotiation in the present invention, and the following embodiment describes the details of the calling access gateway and the called access gateway.

Referring to fig. 13, an embodiment of the calling access gateway in the embodiment of the present invention includes:

the caller fax information collecting module 1301 is configured to obtain caller fax information after a caller establishes a call connection with a called user, where the caller fax information includes a media capability of a caller access gateway, a forwarding capability of a caller session controller SBC, and a caller network status;

a calling processing module 1302, configured to obtain a called query instruction, and generate a calling notification message according to the called query instruction and the fax information of the calling side;

a calling transceiver module 1303, configured to send the calling notification message to the called access gateway, so that the called access gateway obtains called presence information according to the calling notification message, and obtains calling presence information;

the caller transceiving module 1303 is further configured to receive a called notification message sent by the called access gateway, where the called notification message includes called presence information, and the called presence information includes media capability of the called access gateway, forwarding capability of the called SBC, and a called network status.

In the embodiment of the invention, when a calling party mounted on a calling access gateway and a called party mounted on a called access gateway establish call connection, a calling fax information collection module 1301 acquires calling side fax information, a calling transceiver module 1303 informs the called access gateway of the calling side fax information through a calling notification message and instructs the called access gateway to collect the called side fax information, and the called access gateway sends the called side fax information to the calling transceiver module 1301 through a called notification message, so that the called access gateway and the calling access gateway know the fax information of the calling side and the called side before fax negotiation, and when one access gateway is in butt joint with access gateways deployed under multiple operators, fax negotiation messages containing specified codec, packing time length, special a line (such as x-modem) and special fax version information can be flexibly launched according to the capacity of an opposite terminal, the success rate of fax negotiation is improved; in addition, through obtaining the forwarding capability of the SBC by the access gateway, the failure of fax data transmission caused by SBC limitations (for example, SBC needs first packet learning, has codec filtering and network conditions, etc.) in the fax flow can be effectively avoided, and the success rate of fax data transmission is improved.

Optionally, as shown in fig. 14, in some embodiments of the present invention, the calling fax information collecting module 1301 includes: a calling media capability collection unit 1401, a calling forwarding capability collection unit 1402 and a calling network status collection unit 1403;

the caller transceiver module 1303 is further configured to send a caller subscription message to the caller SBC, where the caller subscription message includes a call identifier, so that the caller SBC obtains a caller network status and forwarding capability related to the call identifier according to the caller subscription message;

the caller transceiver module 1303 is further configured to receive, by the caller access gateway, a caller subscription response fed back by the caller SBC, where the caller subscription response includes forwarding capability of the caller SBC and a caller network status;

a calling media capability collecting unit 1401, configured to acquire media capabilities of itself;

a caller forwarding capability collecting unit 1402, configured to analyze the caller subscription response to obtain the forwarding capability of the caller SBC;

a calling network status collecting unit 1403, configured to parse the calling subscription response to obtain the calling network status.

In the embodiment of the present invention, since the calling links of the calling party and the called party are one-to-one during fax, the calling identifier of the call connection is unique, the calling transceiver module 1303 acquires the calling identifier of the current call connection, carries the calling identifier in the calling subscription message, and sends the calling identifier to the calling SBC connected to the calling access gateway, the calling SBC can obtain the forwarding capability related to the call connection according to the calling identifier, and obtain the current calling network status, the calling forwarding capability collection unit 1402 and the calling network status collection unit 1403 obtain the forwarding capability and the calling network status of the calling SBC by analyzing the calling subscription response fed back by the calling SBC, the calling media capability collection unit 1401 can obtain its own media capability through internal detection, and describe in detail how the calling fax information collection module 1301 obtains the calling side fax information, making the solution clearer.

Alternatively, in some embodiments of the present invention,

the calling processing module 1302 is further configured to perform an accurate fax negotiation with the called access gateway according to the calling-side fax information and the called-side fax information.

Alternatively, in some embodiments of the present invention, when the caller SBC needs the first packet learning,

the caller transceiver module 1303 is further configured to receive, through the caller SBC, a first packet sent by the called access gateway after the accurate fax negotiation is completed, where the first packet is used for the caller SBC to learn the first packet.

In the embodiment of the present invention, after the accurate fax negotiation is completed, it is assumed that the T30 fax protocol is selected, but the calling SBC needs the first packet to learn, so that although the fax protocol is completed, the data packet still causes the failure of fax data transmission because the data packet does not know which SBC to send when the fax data is transmitted, and if the called access gateway sends a first packet to the calling SBC for the first packet learning before the fax data is transmitted, the calling transceiver module 1303 can also receive the first packet, so that the fax data transmission can be performed smoothly.

Alternatively, in some embodiments of the present invention,

the calling processing module 1302 is further configured to perform transparent transmission negotiation with the called access gateway according to the calling network status and the called network status, and detect a fax signal tone;

the calling processing module 1302 is further configured to perform fax negotiation with the called access gateway according to the fax signal tone, the fax information of the calling side, and the fax information of the called side.

In the embodiment of the present invention, before fax negotiation, the calling processing module 1302 performs transparent transmission negotiation according to a network condition to detect a fax signal tone, and the calling processing module 1302 performs fax negotiation according to a situation of the fax signal tone by combining factors such as forwarding capability and media capability, so that a rate that best matches the network condition can be selected during fax negotiation, quality in a fax data transmission process can be improved, and a success rate is further improved.

Referring to fig. 15, an embodiment of a called access gateway in the embodiment of the present invention includes:

the called transceiving module 1501 is configured to receive a caller notification message sent by a caller access gateway after a caller establishes a call connection with a called party, where the caller notification message includes a called query instruction and caller-side fax information, and the caller-side fax information includes a media capability of the caller access gateway, a forwarding capability of a caller session controller SBC, and a caller network status;

a called processing module 1502, configured to obtain caller-side presence information and a called query instruction according to the caller notification message;

a called fax information collection module 1503, configured to obtain called-side fax information according to the called query instruction, where the called-side fax information includes a media capability of a called access gateway, a forwarding capability of a called SBC, and a called network status;

the called transceiver module 1501 is further configured to generate a called notification message according to the called-side presence information, and send the called notification message to the calling access gateway.

In the embodiment of the invention, when a calling party mounted on a calling access gateway and a called party mounted on a called access gateway establish call connection, a called transceiver module 1501 receives a calling notification message sent by the calling access gateway, a called processing module 1502 obtains calling side fax information and a called query instruction, a called fax information collection module 1503 obtains called side fax information according to the called query instruction, and a called transceiver module 1501 informs the calling access gateway of the called side fax information through the called notification message, so that the called access gateway and the calling access gateway know the fax information of the calling side and the called side before fax negotiation, so that when one access gateway is in butt joint with access gateways deployed under multiple operators, fax negotiation messages containing information of specified encoding and decoding, packing duration, special a line (such as x-modem) and special fax version information can be flexibly launched according to the capacity of an opposite terminal, the success rate of fax negotiation is improved; in addition, through obtaining the forwarding capability of the SBC by the access gateway, the failure of fax data transmission caused by SBC limitations (for example, SBC needs first packet learning, has codec filtering and network conditions, etc.) in the fax flow can be effectively avoided, and the success rate of fax data transmission is improved.

Optionally, as shown in fig. 16, in some embodiments of the present invention, the called fax information collecting module 1503 includes: called media capability collecting unit 1601, called forwarding capability collecting unit 1602, and called network status collecting unit 1603;

the called transceiver module 1501 is further configured to send a called subscription message to the called SBC according to the called query instruction, where the called subscription message includes a call identifier, so that the called SBC obtains a called network status and forwarding capability related to the call identifier according to the called subscription message;

the called transceiver module 1501 is further configured to receive a called subscription response fed back by the called SBC, where the called subscription response includes forwarding capability of the called SBC and a called network status;

a called media capability collecting unit 1601 configured to obtain a media capability of the user according to the called query instruction;

a called forwarding capability collecting unit 1602, configured to analyze the called subscription response to obtain the forwarding capability of the called SBC;

called network condition collecting unit 1603, configured to parse the called subscription response to obtain the called network condition.

In the embodiment of the present invention, since the call links of the calling party and the called party are one-to-one during fax, the call identifier of the call connection is unique, the called transceiver module 1501 sends a called subscription message to the called SBC according to the called query instruction, the called subscription message includes the call identifier, the called SBC can obtain the forwarding capability related to the call connection according to the call identifier, and obtains the current caller network status, the caller forwarding capability collecting unit 1602 and the caller network status collecting unit 1603 obtain the forwarding capability and the called network status of the called SBC by analyzing the called subscription response fed back by the called SBC, the called media capability collecting unit 1601 obtains the media capability of itself according to the called query instruction, how the called fax information collection module 1503 acquires the called-side fax information is described in detail, so that the scheme is clearer.

Alternatively, in some embodiments of the present invention,

the called processing module 1502 is further configured to perform accurate fax negotiation with the calling access gateway according to the calling-side fax information and the called-side fax information.

the called transceiver module 1501 is further configured to send a first packet to the caller access gateway through the caller SBC after the accurate fax negotiation is completed, where the first packet is used for the caller SBC to learn the first packet.

Alternatively, in some embodiments of the present invention,

the called processing module 1502 is further configured to perform transparent transmission negotiation with the calling access gateway according to the calling network status and the called network status, and detect a fax signal tone;

the called processing module 1502 is further configured to perform fax negotiation with the calling access gateway according to the fax signal tone, the fax information of the calling side, and the fax information of the called side.

It should be noted that, the calling access gateway and the called access gateway, as access gateways, have the same functions and components,

referring to fig. 4, an embodiment of an access gateway entity apparatus according to the embodiment of the present invention includes:

a DSP401, a fax information collector 402, a transceiving interface 403 and a power supply 404;

the functions executed by the processing module in the access gateway are realized by the DSP 401;

the function performed by the fax information collection module in the access gateway is implemented by the fax information collector 402;

the functions performed by the transceiving module in the access gateway are implemented by the transceiving interface 403.

Referring to fig. 17, in the embodiment of the present invention, the connection relationship of the fax system composed of the calling access gateway 1701, the called access gateway 1702, the calling SBC1703 and the called SBC1704 is as follows:

a calling transceiver module 1303 in the calling access gateway 1701 is connected to a calling SBC1703, a calling SBC1603 is connected to a called SBC1704, and the called SBC1704 is connected to a called transceiver module 1501 in the called access gateway 1702.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of accurate facsimile negotiation, comprising:

after a calling user establishes call connection with a called user, before fax negotiation between a called access gateway and a calling access gateway, the calling access gateway acquires calling side fax information, wherein the calling side fax information comprises the media capability of the calling access gateway, the forwarding capability of a calling session controller (SBC) and the calling network condition;

2. The method of claim 1, wherein the obtaining of the caller-side fax information by the caller access gateway comprises:

3. The method of claim 2, wherein after the calling access gateway receives the called notification message sent by the called access gateway, the method further comprises:

4. The method of claim 3, wherein when the caller SBC requires first packet learning,

5. The method of claim 3, wherein the performing of the accurate fax negotiation with the called access gateway by the calling access gateway according to the fax information of the calling side and the fax information of the called side comprises:

6. A method of accurate facsimile negotiation, comprising:

after a calling user establishes call connection with a called user and before fax negotiation between a called access gateway and a calling access gateway, the called access gateway receives a calling notification message sent by the calling access gateway, wherein the calling notification message comprises a called inquiry instruction and calling side fax information, and the calling side fax information comprises the media capability of the calling access gateway, the forwarding capability of a calling session controller (SBC) and the calling network condition;

7. The method of claim 6, wherein the acquiring, by the called access gateway, the fax-related information according to the called inquiry command comprises:

8. The method of claim 7, wherein after the called access gateway generates a called notification message according to the called fax information and sends the called notification message to the calling access gateway, the method further comprises:

9. The method of claim 8, wherein when the caller SBC requires first packet learning,

10. The method of claim 8, wherein the called access gateway performs the accurate fax negotiation with the calling access gateway according to the fax information of the calling side and the fax information of the called side, comprising:

11. A caller access gateway, comprising:

the system comprises a calling fax information collection module, a calling fax information collection module and a calling fax information collection module, wherein the calling fax information collection module is used for acquiring calling side fax information after a calling user establishes call connection with a called user and before a called access gateway and a calling access gateway fax negotiate, and the calling side fax information comprises the media capability of the calling access gateway, the forwarding capability of a calling session controller (SBC) and the calling network condition;

12. The caller access gateway of claim 11, wherein the caller fax information collection module comprises: a calling media capability collecting unit, a calling forwarding capability collecting unit and a calling network condition collecting unit;

the caller transceiver module is further configured to send a caller subscription message to a caller SBC, where the caller subscription message includes a call identifier, so that the caller SBC obtains a caller network status and forwarding capability related to the call identifier according to the caller subscription message;

13. The calling access gateway of claim 12,

14. The caller access gateway according to claim 13, wherein when said caller SBC requires first packet learning,

15. The calling access gateway of claim 14,

16. A called access gateway, comprising:

the called transceiving module is used for receiving a calling notification message sent by a calling access gateway after a calling user establishes call connection with a called user and before fax negotiation between a called access gateway and the calling access gateway, wherein the calling notification message comprises a called inquiry instruction and calling side fax information, and the calling side fax information comprises the media capability of the calling access gateway, the forwarding capability of a calling session controller (SBC) and the calling network condition;

17. The called access gateway of claim 16, wherein the called fax information collecting module comprises: a called media capability collecting unit, a called forwarding capability collecting unit and a called network condition collecting unit;

18. The called access gateway of claim 17,

19. The called access gateway of claim 18, wherein when the caller SBC requires first packet learning,

20. The called access gateway of claim 18,

and the called processing module is also used for carrying out fax negotiation with the calling access gateway according to the fax signal tone, the fax information of the calling side and the fax information of the called side.