Location identification for IP telephony to support emergency services

1. A method for supporting emergency services provided by public safety access points (PSAPs) by locating a telephony subscriber that is using voice over internet protocol (VOIP) services in a telephone network, the method comprising the steps of:

assigning a unique secondary telephone directory number (SDN) to each VOIP access port in addition to a telephone directory number;

storing in a database for each VOIP access port a corresponding SDN and geographic location information;

receiving a first request for emergency services where said first request includes identification of one SDN assigned to the VOIP access port from which the corresponding request for emergency services originated;

determining, based on said one SDN, one PSAP to handle the first request for emergency services;

transmitting to the one PSAP a second request based on the first request, the second request including the directory number of the requesting subscriber and the one SDN;

the one PSAP generating a query to the database to obtain the corresponding geographic location information associated with the one SDN;

the one PSAP receiving a reply to the query containing the geographic location information associated with the one SDN, thereby identifying the location of the requesting subscriber.

2. The method according to claim 1 further comprising registering by the subscriber as a user of the network including determining the SDN of the subscriber's VOW access port based on MAC address of the VOIP access port.

3. The method according to claim 2 further comprising storing the SDN of the registering subscriber in a record associated with the registering subscriber in a subscriber database accessible by a telecommunication switch to handle calls made by the subscriber.

4. The method according to claim 1 wherein the step of receiving the first request includes receiving dialed digits 911 by the subscriber.

5. The method according to claim 1 wherein the step of receiving comprises receiving the first request for emergency services by a public switched telephone network switch which determines, based on said one SDN, the one PSAP to handle the first request for emergency services.

6. A method implemented by a public safety access point (PSAP) for supporting emergency services provided by locating a telephony subscriber that is using voice over internet protocol (VOIP) services in a telephone network, the method comprising the steps of:

receiving a request for emergency services, the request including a directory number and a secondary directory number (SDN) of a subscriber seeking emergency services from a VOIP access port, the SDN being a unique number assigned to said VOIP access port;

generating a query to a database that contains geographic location information corresponding to SDNs;

receiving a reply to the query containing the geographic location information associated with the SDN of the subscriber seeking emergency services, thereby identifying the location of the requesting subscriber so that emergency assistance can be dispatched by an operator of the PSAP.

7. The method according to claim 6 wherein the step of receiving a request includes receiving dialed digits 911 by the subscriber.

8. The method according to claim 6 wherein the step of receiving comprises receiving the request for emergency services by a public switched telephone network switch which determines, based on said SDN, the one PSAP to handle the first request for emergency services.

9. A method for supporting emergency services provided by public safety access points (PSAPs) by locating a telephony subscriber that is using voice over internet protocol (VOIP) services in a telephone network, the method comprising the steps of:

assigning a unique secondary telephone directory number (SDN) to each PSAP;

storing in a database a SDN and geographic location information corresponding to each VOIP access port MAC address;

receiving a first request for emergency services where said first request includes the VOIP access port MAC address from which the corresponding request for emergency services originated;

determining, based on said received VOIP access port MAC address, one PSAP to handle the first request for emergency services;

transmitting to the one PSAP a second request based on the first request, the second request including the directory number of the requesting subscriber and the VOIP access port MAC address;

the one PSAP generating a query to the database to obtain the corresponding geographic location information associated with the VOIP access port MAC address;

the one PSAP receiving a reply to the query containing the geographic location information associated with the one SDN, thereby identifying the location of the requesting subscriber.

10. The method according to claim 9 further comprising registering by the subscriber as a user of the network including determining the SDN of the subscriber's VOIP access port based on MAC address of the VOIP access port.

11. The method according to claim 10 further comprising storing the SDN of the registering subscriber in a record associated with the registering subscriber in a subscriber database accessible by a telecommunication switch to handle calls made by the subscriber.

12. The method according to claim 9 wherein the step of receiving the first request includes receiving dialed digits 911 by the subscriber.

13. The method according to claim 9 wherein the step of receiving comprises receiving the first request for emergency services by a public switched telephone network switch which determines, based on said received VOIP access port MAC address, one PSAP to handle the first request for emergency services.