Internet telephony using network address translation

• US 7,573,873 B1
• Filed: 04/28/2004
• Issued: 08/11/2009
• Est. Priority Date: 05/03/1999
• Status: Expired due to Term

• Current Assignee: Uniloc 2017 LLC (FIG LLC (d/b/a Fortress Investment Group LLC))
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Beser, Nurettin B., Sidhu, Ikhlaq S., Schuster, Guido M., Borella, Michael S.
• Primary Examiner(s): Patel; Jayanti K
• Assistant Examiner(s): Sol; Anthony
• Application Number:
  US10/834,418
• Time in Patent Office: 1,931 Days
• Field of Search: None
• US Class Current: 370/389
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/2514 between local and global IP addresses
• CPC Class Codes: H04L 61/2564 for a higher-layer protocol, e.g. for session initiation protocol [SIP]
• CPC Class Codes: H04L 61/2575 using address mapping retrieval, e.g. simple traversal of user datagram protocol through session traversal utilities for NAT [STUN]
• CPC Class Codes: H04L 61/2585 through application level gateway [ALG]
• CPC Class Codes: H04M 7/1245 where a network other than PSTN/ISDN interconnects two PSTN/ISDN networks

Abstract

A system and method for Internet telephony between a caller station and a callee station are described. The caller station is connected to a first edge network via a first telephony interface, and the callee station is connected to a second edge network via a second telephony interface. An intermediate network is connected to the first edge network via a first router and is connected to the second edge network via a second router. The callee station is associated with a callee station number. The first router initiates the call in response to a setup message that includes the callee station number. A first gatekeeper, controlling the first router, and a second gatekeeper, controlling the second router, together mediate the process of setting up the call. A back end server, in communication with the first and second gatekeepers, stores the addresses and station numbers needed to set up the call. During the call, the first router performs network address translation to transmit signals between the first edge network and the Internet, and the second router performs network address translation to transmit signals between the second edge network and the Internet.

Claims

1. In a communication system comprising a first edge network, a second edge network, a first gatekeeper, a second gatekeeper, and an intermediate network, each of said networks carrying digital data comprising data packets, each of said data packets having a source address and a destination address,

a method for communicating over said intermediate network between a caller station and a callee station, said caller station producing a first caller signal, said caller station being connected to said first edge network, said callee station being accessible via said intermediate network, said caller station being identified on said first edge network by a private caller address and identified on said intermediate network by a proxy public caller address, said callee station being identified on said first edge network by a proxy private callee address and identified on said intermediate network by a proxy public callee address, said caller station being associated with a caller station number, said callee station being associated with a callee station number, said intermediate network being connected to a first router and to a second router, said first router being identified on said intermediate network by a first public router address, said second router being identified on said intermediate network by a second public router address, said method comprising the steps of:

registering said caller station with a server connected to said intermediate network, wherein said intermediate network is connected to said first gatekeeper and to said second gatekeeper, wherein said first gatekeeper is identified by a first public gatekeeper address and controls when said first router allocates proxy public addresses and proxy private addresses from a pool of addresses available to said first router, wherein said second gatekeeper is identified on said intermediate network by a second public gatekeeper address and controls when said second router allocates proxy public addresses and proxy private addresses from a pool of addresses available to said second router, wherein registering said caller station includes (i) transmitting said caller station number, said private caller address, said first public router address, and said first public gatekeeper address to said server, and (ii) said server storing said caller station number, said private caller address, said first public router address, and said first public gatekeeper address transmitted to said server;

registering said callee station with said server connected to said intermediate network, wherein registering said callee station includes (i) transmitting said callee station number, said private callee address, said second public router address, and said second public gatekeeper address to said server, and (ii) said server storing said callee station number, said private callee address, said second public router address, and said second public gatekeeper address transmitted to said server;

after registering said caller station and said callee station with said server, setting up a call from said caller station to said callee station, wherein setting up said call includes (i) said first gatekeeper transmitting to said server a first lookup message including said callee station number and said server responsively sending said second public gatekeeper address to said first gatekeeper, (ii) said first gatekeeper transmitting to said second gatekeeper a setup message including said callee station number, and (iii) said second gatekeeper transmitting to said server a second lookup message including said callee station number included in said setup message, and said server responsively sending said second gatekeeper said private callee address, and

during said call;

A) said first router receiving said first caller signal from said caller station over said first edge network, said first caller signal comprising first caller data packets, said first caller data packets having said private caller address as their source addresses and said proxy private callee address as their destination addresses;

B) for each of said first caller data packets, said first router translating said private caller address into said proxy public caller address and said proxy private callee address into said proxy public callee address, whereby said first router generates second caller data packets;

C) said first router transmitting over said intermediate network to said second router a second caller signal comprising said second caller data packets;

D) said second router receiving said second caller signal from said intermediate network,

E) for each of said second caller data packets, said second router translating said proxy public callee address into said proxy private callee address and said proxy public caller address into said private caller address, whereby said second router generates third caller data packets; and

F) said second router transmitting over said second edge network to said callee station a third caller signal comprising said third caller data packets.

2. The method of claim 1, wherein said caller station is a telephone.

3. The method of claim 1, wherein said caller station is a fax machine.

4. The method of claim 3, wherein said caller signal contains image data encoded in accordance with a facsimile standard.

5. The method of claim 1, wherein said caller station is a modem.

6. The method of claim 1, wherein said caller station is a video device.

7. The method of claim 1, wherein said communication system further comprises a second edge network connected to said intermediate network, said callee station being connected to said second edge network, said callee station being identified on said second edge network by a private callee address, said caller station being identified on said second edge network by a proxy private caller address, said method further comprising the steps of:

receiving said second caller data packets from said intermediate network;

for each of said second caller data packets, translating said proxy public caller address into said proxy private caller address and said proxy public callee address into said private callee address, to provide third caller data packets; and

transmitting said third caller data packets over said second edge network to said callee station.

8. The method of claim 7, further comprising the steps of:

receiving said callee signal from said callee station over said second edge network, said callee signal comprising first callee data packets, said first callee data packets having said private callee address as their source addresses and said proxy private caller address as their destination addresses;

for each of said first callee data packets, translating said private callee address into said proxy public callee address and said proxy private caller address into said proxy public caller address, to provide second callee data packets; and

transmitting said second callee data packets over said intermediate network.

9. The method of claim 8, wherein said callee station is a telephone.

10. The method of claim 8, wherein said callee station is a fax machine.

11. The method of claim 8, wherein said callee station is a modem.

12. The method of claim 8, wherein said callee station is a video device.

13. The method of claim 8, further comprising the step of:

processing said first caller signal into said first caller data packets.

14. The method of claim 13, further comprising the step of:

processing said third callee data packets into a format useable by said caller station.

15. The method of claim 14, further comprising the step of:

processing said first callee signal into said first callee data packets.

16. The method of claim 15, further comprising the step of:

processing said third caller data packets into a format useable by said callee station.

17. The method of claim 1, further comprising:

said server associating said caller station number with said private caller address, said first public router address, and said first public gatekeeper address.

18. The method of claim 1,

wherein said first router and said caller station are connected to a first telephony interface, and

wherein registering said caller station with said server further includes (i) said first telephony interface transmitting a first registration message over said first edge network to said first router, (ii) said first router responsively transmitting a second registration message over said intermediate network to said first public gatekeeper, and then (iii) said first gatekeeper transmitting a third registration message over said intermediate network to said server.

19. The method of claim 18,

wherein said first registration message has said private caller address as its source address, said first private router address as its destination address, and includes said caller station number and said private caller address as its payload,

wherein said second registration message has said first public router address as its source address, said first public gatekeeper address as its destination address, and said caller station number, said private caller address, and said first public router address as its payload, and

wherein said third registration message has said first public gatekeeper address as its source address, said server address as its destination address, and said caller station number, said private caller address, said first public router address, and said first public gatekeeper address as its payload.