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

• US 8,971,314 B2
• Filed: 04/02/2012
• Issued: 03/03/2015
• 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): KASSIM, KHALED M
• Application Number:
  US13/437,244
• Publication Number:
  US 20120188943A1
• Time in Patent Office: 1,065 Days
• Field of Search: 370352-356, 370/329, 370/392
• 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: H04L 65/1104 Session initiation protocol [SIP]
• CPC Class Codes: H04M 7/006 Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42
• 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]

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 call protocol conversion gateway, comprising:

a mobile switching center to receive a VoIP call over signaling system number 7 (SS7)—

based call signaling;

a SS7-to-SIP gateway to convert said SS7 ISUP based call signaling into session initiation protocol (SIP)—

based call signaling, and to pass said SIP call signaling to a voice over Internet (VoIP) positioning center (VPC);

wherein the VoIP positioning center (VPC) assigns routing based upon the location retrieved from a location information service/subscriber line database (LIS/SLDB)

wherein said SS7-to-SIP gateway converts an emergency services query key (ESQK) into an emergency services routing key (ESRK), and provides said converted ESRK to said mobile switching center for passage to an appropriate selective router.

2. The call protocol conversion gateway according to claim 1, wherein:

said VoIP call is a wireless 911 call.

3. The call protocol conversion gateway according to claim 1, wherein:

said VoIP call is a VoIP wireless call made via a local area network.

4. The call protocol conversion gateway according to claim 3, wherein:

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

11. The call protocol conversion gateway according to claim 1, wherein:

said SS7-to-SIP gateway further converts an emergency services routing number (ESRN) into a trunk select code, and provides said converted trunk select code to said mobile switching center for passage to an appropriate selective router.

5. A method of converting a VoIP call, passed over a switched telephone network, into SS7 call signaling for presentation to a public safety access point (PSAP), comprising:

receiving a voice over Internet protocol (VoIP) call from a VoIP phone via a SS7-based call signaling network;

converting said SS7 call signaling into session initiation protocol (SIP)-based call signaling;

assigning, by a VoIP positioning center (VPC), routing, based upon the location retrieved from a location information service/subscriber line database (LIS/SLDB)

converting an emergency services query key (ESQK) into an emergency services routing key (ESRK); and

routing said converted ESRK over an appropriate selective router.

6. The method of converting a VoIP call, passed over a switched telephone network, into SS7 call signaling for presentation to a public safety access point (PSAP) according to claim 5, wherein:

said VoIP call is received from a wireless fidelity (WiFi) network.

7. The method of converting a VoIP call, passed over a switched telephone network, into SS7 call signaling for presentation to a public safety access point (PSAP) according to claim 5, wherein:

said VoIP phone is a wireless phone.

8. The method of converting a VoIP call, passed over a switched telephone network, into SS7 call signaling for presentation to a public safety access point (PSAP) according to claim 5, wherein:

said VoIP phone is a dual mode phone.

9. The method of converting a VoIP call, passed over a switched telephone network, into SS7 call signaling for presentation to a public safety access point (PSAP) according to claim 8, 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.

10. The method of converting a VoIP call, passed over a switched telephone network, into SS7 call signaling for presentation to a public safety access point (PSAP) according to claim 6, further comprising:

assigning said routing based upon a location retrieved from said converted location information service/subscriber line database (LIS/SLDB) location information.

12. The call protocol conversion gateway according to claim 5, further comprising:

converting an emergency services routing number (ESRN) into a trunk select code, and providing said converted trunk select code to said mobile switching center for passage to an appropriate selective router.