Real-time facsimile transmission over a packet network

• US 9,094,419 B2
• Filed: 11/10/2010
• Issued: 07/28/2015
• Est. Priority Date: 11/10/2009
• Status: Active Grant

• Current Assignee: NetGen Communications, Inc.
• Original Assignee: NetGen Communications, Inc.
• Inventors: Coffee, Michael B., Schornak, Clifford J.
• Primary Examiner(s): Jiang, Charles C
• Assistant Examiner(s): DEFAUW, THAD N
• Application Number:
  US12/943,297
• Publication Number:
  US 20110109936A1
• Time in Patent Office: 1,721 Days
• US Class Current: 1/1
• CPC Class Codes: H04L 65/103 in the network
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04L 65/40 Support for services or applications
• CPC Class Codes: H04N 1/00214 details of transmission
• CPC Class Codes: H04N 1/0022 involving facsimile protocols or a combination of facsimile protocols and computer data transmission protocols
• CPC Class Codes: H04N 2201/0015 Control of image communication with the connected apparatus, e.g. signalling capability
• CPC Class Codes: H04N 2201/0024 Converting image communication control signals, e.g. group 3 facsimile protocol signals, to non-image communication control signals or vice versa

Abstract

Various methods and systems are provided for real-time facsimile (fax) transmission over a packet network. In one embodiment, among others, a method includes monitoring fax communications across a pass-through connection and controlling transfer of the fax communications to a fax-relay protocol connection based at least in part upon the monitored fax communications. In another embodiment, a method includes monitoring a state of a state machine communicating over a pass-through connection and, responsive to a re-invite to the fax-relay protocol, transferring from the pass-through connection to a fax-relay protocol connection based at least in part upon the state of the state machine.

Claims

1. A gateway, comprising:

a modem configured to examine communications of an endpoint fax terminal; and

a state observer configured to;

monitor media stream communications of the endpoint fax terminal that are transmitted across a pass-through connection between the gateway and a corresponding packet network device that is a server or another gateway, the monitored media stream communications indicating a state of the endpoint fax terminal; and

control transfer of the media stream communications from the pass-through connection to a fax-relay protocol connection between the gateway and the corresponding packet network device in response to a re-invite to a fax-relay protocol, where rejection of the re-invite is based at least in part upon the endpoint fax terminal having entered a negotiation phase via the pass-through connection as indicated by detection of a digital command signal (DCS) message being communicated via the monitored media stream communications in response to a digital identification signal (DIS) message.

2. The gateway of claim 1, wherein the fax-relay protocol connection is a T.38 connection.

3. The gateway of claim 1, wherein the monitored media stream communications include V.21 flags.

4. The gateway of claim 1, wherein the state observer tracks a current observer state associated with the state of the endpoint fax terminal, the current observer state determined based at least in part upon the monitored media stream communications.

5. The gateway of claim 4, wherein the state observer is configured to transition the current observer state in response to the monitored media stream communications.

6. The gateway of claim 4, wherein the state observer is configured to allow acceptance of the re-invite to the fax-relay protocol by the gateway based upon the current observer state, acceptance of the re-invite to the fax-relay protocol initiating transfer of the media stream communications from the pass-through connection to the fax-relay protocol connection.

7. The gateway of claim 6, wherein the gateway is configured to spoof a fax call menu (CM) if the re-invite to the fax-relay protocol has been rejected.

8. The gateway of claim 4, wherein the state observer is configured to prevent acceptance of the re-invite to the fax-relay protocol by the gateway based upon the current observer state, the re-invite to the fax-relay protocol requesting transfer of the media stream communications from the pass-through connection to the fax-relay protocol connection.

9. A gateway, comprising:

a modem configured to examine communications of an endpoint fax terminal; and

a state observer configured to;

monitor media stream communications of the endpoint fax terminal that are transmitted across a pass-through connection between the gateway and a corresponding packet network device that is a server or another gateway, the monitored media stream communications indicating a state of the endpoint fax terminal associated with a current observer state; and

control transfer of the media stream communications from the pass-through connection to a fax-relay protocol connection between the gateway and the corresponding packet network device based at least in part upon the monitored media stream communications, where the gateway is configured to allow acceptance of a re-invite to a fax-relay protocol by the gateway based upon the current observer state, acceptance of the re-invite initiating transfer of the media stream communications from the pass-through connection to the fax-relay protocol connection, and suppress a digital identification signal (DIS) if the re-invite to the fax-relay protocol has not been accepted.

10. A fax server, comprising:

a virtual endpoint fax terminal including a fax application and a T.30 subsystem; and

a state observer configured to;

monitor a state of the virtual endpoint fax terminal based at least in part upon indications from the T.30 subsystem and a signaling entity of the fax server, the indications based at least in part upon media stream communications of the virtual endpoint fax terminal that are communicated across a pass-through connection between the fax server and a corresponding packet network device that is another server or a gateway; and

control transfer of the media stream communications of the virtual endpoint fax terminal from the pass-through connection to a fax-relay protocol connection between the fax server and the corresponding packet network device in response to a re-invite to a fax-relay protocol, where rejection of the re-invite is based at least in part upon the virtual endpoint fax terminal having entered a pass-through negotiation state as indicated by the T.30 subsystem and the signaling entity based upon detection of a digital command signal (DCS) message being communicated across the pass-through connection in response to a digital identification signal (DIS) message.

11. The fax server of claim 10, wherein the fax-relay protocol connection is a T.38 connection.

12. The fax server of claim 10, wherein the state observer tracks a current observer state associated with the state of the virtual endpoint fax terminal, the current observer state determined based at least in part upon the indications from the T.30 subsystem and the signaling entity.

13. The fax server of claim 12, wherein the state observer is configured to transition the current observer state in response to the indications from the T.30 subsystem and the signaling entity.

14. The fax server of claim 12, wherein the state observer is configured to allow acceptance of the re-invite to the fax-relay protocol by the fax server based upon the current observer state, acceptance of the re-invite to the fax-relay protocol initiating transfer of the media stream communications from the pass-through connection to the fax-relay protocol connection.

15. The fax server of claim 12, wherein the state observer is configured to prevent acceptance of the re-invite to the fax-relay protocol by the fax server based upon the current observer state, the re-invite to the fax-relay protocol requesting transfer of the media stream communications from the pass-through connection to the fax-relay protocol connection.

16. The fax server of claim 15, wherein the fax server is configured to spoof a fax call menu if the re-invite to the fax-relay protocol has been rejected.

17. The fax server of claim 10, wherein the signaling entity is a SIP entity.

18. A fax server, comprising:

a virtual endpoint fax terminal including a fax application and a T.30 subsystem; and

a state observer configured to;

monitor a state of the virtual endpoint fax terminal based at least in part upon indications from the T.30 subsystem and a signaling entity, the state of the virtual endpoint fax terminal associated with a current observer state; and

control transfer of media stream communications of the virtual endpoint fax terminal from a pass-through connection between the fax server and a corresponding packet network device that is another server or a gateway, to a fax-relay protocol connection between the fax server and the corresponding packet network device based at least in part upon the indications from the T.30 subsystem and the signaling entity, where the state observer is configured to allow acceptance of a re-invite to a fax-relay protocol by the fax server based upon the current observer state, the re-invite to the fax-relay protocol requesting transfer of the media stream communications from the pass-through connection to the fax-relay protocol connection, and the fax server is configured to suppress a digital identification (DIS) signal if the re-invite to the fax-relay protocol has not been accepted.

19. A method, comprising:

monitoring fax media stream communications of an endpoint fax terminal that are transmitted across a G.711 pass-through connection between two packet network devices comprising a gateway, a server, or both; and

controlling transfer of the fax media stream communications from the G.711 pass-through connection to a fax-relay protocol connection between the two packet network devices in response to a re-invite to a fax-relay protocol, where rejection of the re-invite is based at least in part upon the endpoint fax terminal having entered a negotiation phase via the G.711 pass-through connection as indicated by detection of a digital command signal (DCS) message being communicated via the monitored fax media stream communications in response to a digital identification signal (DIS) message.

20. The method of claim 19, further comprising determining a current state based at least in part upon the monitored fax media stream communications.

21. The method of claim 20, wherein the current state is associated with a state of an endpoint fax terminal communicating across the G.711 pass-through connection.

22. The method of claim 20, wherein the current state is associated with a state of a fax application communicating across the G.711 pass-through connection.

23. The method of claim 20, wherein transfer of the fax media stream communications is controlled based at least in part upon the current state.

24. The method of claim 20, further comprising:

receiving the re-invite to the fax-relay protocol requesting transfer of the fax media stream communications from the G.711 pass-through connection to the fax-relay protocol connection; and

accepting the re-invite to the fax-relay protocol to initiate transfer from the G.711 pass-through connection to the fax-relay protocol connection based at least in part upon the current state.

25. The method of claim 20, further comprising:

receiving the re-invite to the fax-relay protocol requesting transfer of the fax media stream communications from the G.711 pass-through connection to the fax-relay protocol connection; and

rejecting the re-invite to the fax-relay protocol to prevent transfer from the G.711 pass-through connection to the fax-relay protocol connection based at least in part upon the current state.

26. The method of claim 20, further comprising sending the re-invite to the fax-relay protocol based at least in part upon the current state, the re-invite to the fax-relay protocol requesting transfer of the fax media stream communications from the G.711 pass-through connection to the fax-relay protocol connection.

27. The method of claim 26, further comprising spoofing a fax call menu (CM) if the re-invite to the fax-relay protocol has been rejected.

28. The method of claim 19, wherein the endpoint fax terminal is a virtual endpoint fax terminal.

29. A method, comprising:

monitoring fax media stream communications across a G.711 pass-through connection between two packet network devices comprising a gateway, a server, or both;

determining a current state based at least in part upon the monitored fax media stream communications;

receiving a re-invite to a fax-relay protocol requesting transfer of the fax media stream communications from the G.711 pass-through connection to a fax-relay protocol connection between the two packet network devices;

controlling transfer of the fax media stream communications from the G.711 pass-through connection to the fax-relay protocol connection based at least in part upon the current state; and

suppressing a digital identification signal (DIS) if the re-invite to the fax-relay protocol has not been accepted.

30. A method, comprising:

monitoring a state of a state machine communicating over a pass-through connection between two packet network devices comprising a gateway, a server, or both; and

in response to acceptance of a re-invite to a fax-relay protocol, transferring communications of the state machine from the pass-through connection to a fax-relay protocol connection between the two packet network devices, where the re-invite is rejected if a pass-through negotiation state has been entered as indicated by the state of the state machine, where initiation of the pass-through negotiation state is based upon detection of a digital command signal (DCS) message being communicated across the pass-through connection in response to a digital identification signal (DIS) message.

31. The method of claim 30, wherein monitoring the state of the state machine comprises:

monitoring state machine communications across the pass-through connection; and

tracking a current state of the state machine, the current state determined based at least in part upon the monitored state machine communications.

32. The method of claim 31, wherein the current state transitions in response to the monitored state machine communications.

33. The method of claim 30, further comprising:

receiving the re-invite to the fax-relay protocol requesting transfer from the pass-through connection to the fax-relay protocol connection, where acceptance of the re-invite to the fax-relay protocol initiates transfer to the fax-relay protocol connection.

34. The method of claim 30, further comprising sending the re-invite to the fax-relay protocol based at least in part upon the state of the state machine, the re-invite to the fax-relay protocol requesting transfer from the pass-through connection to the fax-relay protocol connection.

35. A method, comprising:

monitoring a fax media stream session across a G.711 pass-through connection, the fax media stream session including a plurality of packets communicated across the G.711 pass-through connection;

detecting a V.21 frame in a packet communicated via the fax media stream session, where the V.21 frame is not a digital command signal (DCS); and

in response to detecting the V.21 frame, providing an indicator to reset a jitter buffer associated with the G.711 pass-through connection.

36. The method of claim 35, wherein the jitter buffer is in a gateway in communication with an endpoint fax terminal.

37. The method of claim 35, wherein the jitter buffer is in a fax server.

38. A method, comprising:

monitoring a fax media stream session across a G.711 pass-through connection using a V.34 modulation scheme, the fax media stream session including a plurality of packets communicated across the G.711 pass-through connection;

detecting a high-band QAM signal termination or a low-band QAM signal termination in a packet communicated via the fax media stream session; and

in response to detecting the high-band QAM signal termination or the low-band QAM signal termination, providing an indicator to reset a jitter buffer associated with the G.711 pass-through connection.

39. The method of claim 38, further comprising clearing the indicator prior to the start of a subsequent signal.

40. The method of claim 38, wherein the jitter buffer is in a gateway in communication with an endpoint fax terminal.

41. The method of claim 38, wherein the jitter buffer is in a fax server.

42. A method, comprising:

monitoring a fax session across a G.711 media stream, the fax session including a plurality of packets communicated across the G.711 media stream;

determining that the fax session is using a V.8 specification to negotiate the fax session; and

corrupting the G.711 media stream to inhibit V.8 negotiation until a call control entity has negotiated a transition to a fax-relay protocol.

43. The method of claim 42, wherein the method is independent of call control procedures implemented by an on-ramp gateway or an off-ramp gateway.