Services implemented by Extensions

i.e., new methods and headers

See the activities of the IETF SIP, SIPPING, and SIMPLE working groups

Proxy servers - simply treat unknown methods as an OPTION request, unless there is a Proxy-Require header.

User agents return:

405	Method Not Allowed	if the method is recognized, but not supported
500	Bad Request	if it does not recognize the method
420	Bad Extension	if the UAS does not support the requested feature

All SIP extensions which use the Require or Supported header must be documented as an RFC - to prevent interoperability problems

All standardized SIP extensions must document how the extension interacts with elements that don’t understand this extension

Transcript

[slide327] We can implement a bunch of extensions, but because not everyone may support those extensions, we might have to say, no, I don't support that method, or it's a bad request, or it's an extension that I don't support.