Establishing an IP session between a host using SIP and a device without an IP address

1. A method of initiating an Internet Protocol (IP) session between a host using a session initiation protocol and a device without an IP address, the method comprising the steps of:

receiving at a relay, via an IP connection, a SIP INVITE request originated by the host that includes a host contact that corresponds to the host and a device identifier that corresponds to the device;

parsing, at the relay, the SIP INVITE request to determine said device identifier;

preparing, at the relay, a message for the device that includes said SIP INVITE request; and

forwarding said message from the relay to the device via a non-IP connection, said message resulting in the device obtaining a device IP address and sending an acknowledgment of the SIP INVITE request that includes said device IP address.

2. The method of claim 1 wherein said forwarding said message from the relay to the device utilizes a short messaging service message.

3. The method of claim 2 wherein said message is an Over The Air-Wireless Session Protocol Packet Data Unit message that encapsulates the SIP INVITE request.

4. The method of claim 1 wherein said device is a packet data enabled mobile station.

5. The method of claim 1 further comprising the steps of registering with a SIP Registrar a plurality of contacts for the device where at least one contact of said plurality of contacts points to the relay.

6. The method of claim 5 wherein the at least one contact of said plurality of contacts has a priority lower than an other contact of said plurality of contacts.

7. The method of claim 1 wherein obtaining a device IP address comprises extracting said SIP INVITE request from said message and activating a packet data protocol (PDP) context.

8. An apparatus for enabling the establishment of an Internet Protocol (IP) session between a host using a session initiation protocol and a device without an IP address, the apparatus comprising in combination:

a network interface for receiving, via an IP connection, a SIP INVITE request originated by the host that includes a host contact corresponding to the host and a device identifier corresponding to the device;

a controller, coupled to said network interface, for

parsing the SIP INVITE request to determine said device identifier;

preparing a message for the device that includes said device identifier and said SIP INVITE request, and

presenting said message to said network interface, said message to be delivered from the apparatus to the device via a non-IP connection and to result in the device obtaining a device IP address and sending an acknowledgment of the SIP INVITE request that includes said device IP address.

9. The apparatus of claim 8 wherein said message is to be delivered from the apparatus to the device via a short messaging service center in the form of short messaging service message.

10. The apparatus of claim 9 wherein said message is an Over the Air-Wireless Session Protocol Packet Data Unit message that encapsulates the SIP INVITE request.

11. The apparatus of claim 8 wherein said device is a packet data enabled mobile station.

12. The apparatus of claim 8 wherein said device IP address is an IPv4 address, and said acknowledgment is a SIP:OK message.

13. The apparatus of claim 8 wherein said network interface receives said SIP INVITE request addressed to a user name corresponding to said device identifier and said controller prepares said message as an over the air wireless services protocol packet data unit that encapsulates said SIP INVITE request as the payload and presents, via said network interface, said message to a short message services center for delivery to the device as a short messaging services message.

14. The apparatus of claim 8 wherein said SIP INVITE request is received by the apparatus as a result of a SIP registrar including a SIP Contact corresponding to the device, said SIP Contact including a host name corresponding to the apparatus.

15. The apparatus of claim 8 wherein said message is a Short Messaging Service message that include an Over The Air-Wireless Session Protocol Packet Data Unit that encapsulates said SIP INVITE request.