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

• US 9,344,578 B2
• Filed: 05/27/2014
• Issued: 05/17/2016
• Est. Priority Date: 04/04/2006
• Status: Expired due to Fees

• Current Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Original Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Inventors: Mitchell, Don
• Primary Examiner(s): Jagannathan, Melanie
• Application Number:
  US14/287,561
• Publication Number:
  US 20140269511A1
• Time in Patent Office: 721 Days
• US Class Current: 1/1
• 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 of converting call protocol at a conversion gateway, comprising:

receiving, at a mobile switching center, a Voice Over Internet Protocol (VoIP) call;

converting, at a conversion gateway, said VoIp call into an SS7 ANSI-41 J-STD-036 transaction capability application part (TCAP)-based call;

transmitting Session Initiation Protocol (SIP) call signaling associated with said VoIP call to a Voice Over Internet Protocol (VoIP) positioning center to retrieve routing information associated with said call;

receiving an emergency services query key (ESQK) and an emergency services routing number (ESRN) relating to said VoIP call from said VoIP positioning center;

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

translating said ESRN into a trunk select code; and

routing said converted SS7 ANSI-41 J-STD-036 transaction capability application part (TCAP)-based call, based on said translated ESRK and said translated trunk select code.

2. The method of converting call protocol at a conversion gateway according to claim 1, wherein:

said call is a wireless 911 call.

3. The method of converting call protocol at a conversion gateway according to claim 1, further comprising:

providing an i1 public switched telephone network (PSTN) number relating to said VoIP call, back to said mobile switching center.

4. The method of converting call protocol at a conversion gateway according to claim 1, wherein:

said PSTN number is a last routing option (LRO) phone number.