SS7 ANSI-41 to SIP based call signaling conversion gateway for wireless VoIP E911

• US 8,774,171 B2
• Filed: 07/18/2012
• Issued: 07/08/2014
• Est. Priority Date: 04/04/2006
• Status: Active Grant

• Current Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Original Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Inventors: Mitchell, Don
• Primary Examiner(s): Nawaz, Asad
• Assistant Examiner(s): HAMEL, JOEL A
• Application Number:
  US13/552,079
• Publication Number:
  US 20120282881A1
• Time in Patent Office: 720 Days
• Field of Search: 370352-356, 370466-467, 379/45, 455/414.4, 455/521
• US Class Current: 370/352
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04M 7/0066 Details of access arrangements to the networks where the access arrangement is a PSTN/ISDN access H04M7/122
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 88/16 Gateway arrangements

Abstract

An SS7-based call protocol conversion gateway that translates between circuit-switched SS7 protocols and session initiation protocol (SIP) oriented protocol, allowing an E911 call initiated over a switched network to be routed by a VoIP network. The SS7-based call protocol conversion gateway provides a PSAP with MSAG quality (street address) information about a VoIP dual mode phone user without the need for a wireless carrier to invest in building out an entire VoIP core. Thus, wireless carriers may continue signaling the way they are today, i.e., using the J-STD-036 standard for CDMA and GSM in North America, yet see benefits of a VoIP network core, i.e., provision of MSAG quality location data to a PSAP.

Claims

1. A method to convert a VoIP call, passed over a switched telephone network, into a VoIP call for presentation to a public safety access point (PSAP), comprising:

receiving a VoIP 911 originating call to be converted to signaling system number 7 (SS7) ANSI-41 J-STD-036 transaction capability application part (TCAP)-based call signaling;

converting said VoIP 911 call using SS7 ANSI-41 J-STD-036 TCAP-based call signaling into session initiation protocol (SIP) call signaling; and

transmitting said SS7 ANSI-41 J-STD-036 transaction capability application part (TCAP)-to-SIP converted call signaling associated with said VoIP 911 originating call to a physical VoIP positioning center to retrieve routing information associated with said VoIP 911 originating call;

receiving routing instruction including an emergency services query key (ESQK) and a trunk select code; and

translating said ESQK into an emergency services routing key (ESRK).

2. The method to convert a VoIP call, passed over a switched telephone network, into a VoIP call for presentation to a public safety access point (PSAP) according to claim 1, wherein:

said local area network is a wireless fidelity (WiFi) network.

3. The method to convert a VoIP call, passed over a switched telephone network, into a VoIP call for presentation to a public safety access point (PSAP) according to claim 1, wherein:

said physical VoIP phone is a dual mode wireless phone.

4. The method to convert a VoIP call, passed over a switched telephone network, into a VoIP call for presentation to a public safety access point (PSAP) according to claim 1, wherein:

said dual mode phone has a first mode operable in a cellular phone network, and a second mode operable in a wireless fidelity (WiFi) network.

5. A method to convert a VoIP call, passed over a switched telephone network, into a VoIP call for presentation to a public safety access point (PSAP), comprising:

receiving a voice over Internet protocol (VoIP) call from a VoIP phone;

routing said VoIP call using signaling system number 7 (SS7) ANSI-41 J-STD-036 transaction capability application part (TCAP)-based call signaling;

converting said SS7 ANSI-41 J-STD-036 TCAP-based call signaling into session initiation protocol (SIP) call signaling;

means for passing said SIP call signaling to a VoIP positioning center;

receiving routing instruction from a VoIP positioning center (VPC), including an emergency services query key (ESQK) a trunk select code; and

translating said ESQK into an emergency services routing key (ESRK).

6. The method to convert a VoIP call, passed over a switched telephone network, into a VoIP call for presentation to a public safety access point (PSAP) according to claim 5, further comprising:

egressing said VoIP call based upon said ESRK and said trunk select code to a proper PSAP.