SS7 ANSI-41 to SIP based call signaling conversion gateway for wireless VoIP E911
View Patent ↗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.
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.