Re: [Sip] Can we use From Header's value to build Contact in REFER

The From header field is likely (but not guaranteed) to contain something with AOR properties, and you want an identifier that corresponds to

exactly the endpoint that sent the REFER.

You're better off rejecting such a REFER as malformed.

The same is true of SUBSCRIBE, and because of forking, initial NOTIFYs.

You could consider being more lenient if Contact is missing in subsequent NOTIFYs, using the remote target already stored in the dialog, but

remember that you'd be writing code to deal with a peer that is not following the protocol and that other exceptions are quite likely.

RjS

On Feb 8, 2009, at 11:17 PM, <sunil.bhagat at wipro.com> <sunil.bhagat at wipro.com> wrote:

Hi All.

I have a small query regarding the Contact Header while building a REFER message.
RFC 3515 specifies that Contact Header is mandatory in REFER message.
If Contact Header is missing in REFER, can we populate its value from the “From” Header?

If yes, Can the same be done for SUBSCRIBE and NOTIFY messages?

Thanks,
Sunil

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