[SIPForum-discussion] difference between Allow, Supported, Options and Require header

[Murali Vuppandla]

Here is the brief description.

 

Allow: Allow header is used to mention what methods an UA does support. And
this methods can be used in that particular  dialog. If the Allow header is
not present, then it doesn't mean that UA won't support any methods.

 

Ex:  Allow: INVITE,BYE,CANCEL.

 

Supported: It says what extensions can be supported by an UA.

 

Ex: Supported: 100rel

 

Require: It lists all the extensions that other UA must support in order to
process the request. Another similar header Proxy-Require is also there. In
this case Proxy should support the extensions listed to process the request
received.

 

Options : It's a method which is used to query the capabilities of the other
party. Say if want to know whether or not the end party supports G711 codec
(it can also query Method, Extensions etc.), you can send OPTIONS method
querying the capabilities. In this scenario no need to send INVITE. This is
one of the advantages of OPTIONS method. I think it's mandatory that every
UA should support OPTIONS.

 

Regards,

Murali.

 

 

From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of gaurav ahuja
Sent: Wednesday, February 10, 2010 11:45 AM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] difference between Allow, Supported, Options
and Require header

 

Hello All,

 

I am confused between when we implement Allow, Supported, Options and
Require Header.

 

Also how these headers are different from each other?

 

Thanks & Regards,

Gaurav Ahuja

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