Providing content delivery during a call hold condition

1. A method comprising:

receiving a request message for content from a proxy server that is configured to transmit the request message during a hold condition of a voice call established between a first user agent and a second user agent over a data network, wherein a type of the content is selected by the proxy server via a packet header extension in the request message; and

communicating with the second user agent, via the proxy server, to establish a media session with the second user agent for transmitting the content, wherein the proxy server is configured to instruct the second user agent to stop transmitting media for the voice call.

2. A method according to claim 1 , wherein the first user agent notifies the proxy server of the hold condition, the proxy server being further configured to perform call control on behalf of the first user agent.

3. A method according to claim 1 , wherein the establishment of the voice call and the media session is according to Session Initiation Protocol (SIP), and the content includes music.

4. A method according to claim 3 , wherein the request message is a first INVITE message, the establishment of the media session includes,

transmitting a 200 OK message in response to first INVITE message to the proxy server, wherein the proxy server is further configured to transmit a second INVITE message to the second user agent.

5. A method according to claim 4 , wherein the second user agent responds to the second INVITE message with another 200 OK message to the proxy server forwarding to the first user agent, wherein the proxy server is further configured to generate an ACK message, the method further comprising:

receiving the ACK message; and

retrieving the content; and

transmitting the content over the media session to the second user agent.

6. A method according to claim 3 , wherein the content further includes advertisements.

7. A method according to claim 1 , wherein the first user agent notifies the proxy server of the hold condition, the proxy server being configured to perform call control on behalf of the first user agent.

8. An apparatus comprising:

a memory configured to store content;

a processor coupled to the memory and configured to receive a request message for the content from a proxy server that is configured to initiate the request message during a hold condition of a voice call established between a first user agent and a second user agent over a data network, wherein a type of the content is specified by the proxy server, via an extension in the request message; and

a communication interface coupled to the processor and configured to communicate with the second user agent, via the proxy server, to establish a media session with the second user agent for transmitting the content, wherein the proxy server is configured to instruct the second user agent to stop transmitting media for the voice call.

9. An apparatus according to claim 8 , wherein the first user agent notifies the proxy server of the hold condition, the proxy server being further configured to perform call control on behalf of the first user agent.

10. An apparatus according to claim 8 , wherein the establishment of the voice call and the media session is according to Session Initiation Protocol (SIP), and the content includes music.

11. An apparatus according to claim 10 , wherein the request message is a first INVITE message, and the communication interface, in support of establishing the media session, is further configured to transmit a 200 OK message in response to first INVITE message to the proxy server, wherein the proxy server is further configured to transmit a second INVITE message to the second user agent.

12. An apparatus according to claim 11 , wherein the second user agent responds to the second INVITE message with another 200 OK message to the proxy server forwarding to the first user agent, wherein the proxy server is further configured to generate an ACK message, the processor being further configured to receive the ACK message, to retrieve the content, the communication interface being further configured to transmit the content over the media session to the second user agent.

13. An apparatus according to claim 10 , wherein the content further includes advertisements.

14. An apparatus according to claim 8 , wherein the first user agent notifies the proxy server of the hold condition, the proxy server being configured to perform call control on behalf of the first user agent.

15. An apparatus according to claim 8 , wherein the apparatus is a content server, and the proxy server is maintained by a service provider.

16. An apparatus according to claim 15 , wherein the content server is provided by a third party.

17. A method comprising:

detecting, at a proxy server within a service provider network, a hold condition for a packetized voice call between voice stations; and

facilitating, via the proxy server, establishment of a media session with a content device to deliver content to one of the voice stations that is on hold, wherein a type of the content is specified by the proxy server via a packet header extension in a request message.

18. A method according to claim 17 , wherein the proxy server is configured to perform call control on behalf of the voice stations.

19. A system comprising:

a proxy server, within a service provider network, configured to detect a hold condition for a packetized voice call between voice stations to facilitate establishment of a media session with a content device to deliver content to one of the voice stations that is on hold, wherein a type of the content is specified by the proxy server via a packet header extension in a request message.

20. A system according to claim 19 , wherein the proxy server is configured to perform call control on behalf of the voice stations.

21. A method according to claim 1 , wherein a specific content file is referenced via a Uniform Reference Locator (URL).