Olaf Bergmann wrote:

x-ser@sidell.org wrote:

...

For outbound pstn calls, I want to change the INVITE message's From: header field to specify my caller id. For example, I want to change it from this:

From: 201 sip:201@67.32.47.145:5060;tag=4f3c1a5892c015f

to this:

From: Forte Inc sip:9195551234@67.32.47.145:5060;tag=4f3c1a5892c015f

What's the best way to change the "comment" and LHS of the address?

The general recommendation is not to do this. Besides RFC-2543-related reasons, a compelling argument is that the branch tag created by SER is (IIRC) built from a hash over specific parts of the From field.

Regards, Olaf _______________________________________________ Serusers mailing list Serusers@lists.iptel.org http://lists.iptel.org/mailman/listinfo/serusers

Out of curiosity, is this just a limitation because of the way SER handles it? Reading 2543, I simply see:

"Call-ID, To and From are needed to identify a call leg. The distinction between call and call leg matters in calls with multiple responses to a forked request. The format is similar to the equivalent RFC 822 [24] header, but with a URI instead of just an email address."

There's a reference that the tag header MAY (or may not) be used in a URI, but MUST be used if one is to identify unique calls from the same location, which to me implies that the important part of the From/To headers for identification is the tag.

"The "tag" MAY appear in the From field of a request. It MUST be present when it is possible that two instances of a user sharing a SIP address can make call invitations with the same Call-ID."

The implication of this is that the ENTIRE From/To headers are not necessarily immutable, as the tag is used to identify them as unique.

The question is, is there something elsewhere which contradicts this (and therefore enforced the rule of immutable From/To headers), or is this just a SER idiosyncrasy? If it's just a SER thing, might it not be different in other systems (something we might have to watch out for), or might it not be coded around within SER to allow modification of the From header?

While I'm not in a rush to go out and change headers, I was just curious.

N.

x-ser@sidell.org wrote:

On Tue, 02 Oct 2007 09:30:16 +0200, Olaf Bergmann wrote:

...

The general recommendation is not to do this.

Thanks. I'm still at the bottom of the learning curve here. Looks like the correct way to set the pstn caller id is to insert a Remote-Party-ID field.

Yes. Or use P-Asserted-Identity (cf RFC 3325), an outcome of the awful 3GPP efforts for regulating the public Internet. RPID is defined in an I-D that has expired long time ago.

Regards, Olaf