[asterisk-users] Wanted a modified SIP message body

[Kevin P. Fleming]

On 08/31/2011 02:46 AM, Jaime Lozano wrote:
> Hello,
> I agree with you, I'm not explaining the problem in a proper manner,
> because of my lack of Asterisk knowings. I send the Wireshark captures.
>
> 3com telephones take the timezone TZ:7200 from the 3Com PBX to show the
> time right. But what if I want a 3Com telephone to work with Asterisk
> PBX? Then the telephone time is wrong, 2 hours lower. It seems 3Com
> telephones need the TZ:7200. 3Com telephones work with Asterisk and it
> is great, but we would like to log the calls.

OK, so the first clarification is that you are talking about responses 
to REGISTER requests specifically, not all responses to all requests. 
That's good :-)

On to the meat of the issue... indeed, the '200 OK' response to a 
REGISTER request does not normally have a message body; nothing in the 
SIP RFCs even suggests that there would be one (although it's certainly 
allowed should the registrar want to include it) or what would be 
present in it.

As has been previously replied here, there is no facility in Asterisk to 
include a message body in a REGISTER request response, so providing one 
will definitely require source code modifications. They wouldn't be 
terribly difficult, but they would only be applicable to these 
particular phones, which reduces the benefit of making the changes to 
the community at large.

With that said... it's certainly possible to do this, but it's going to 
take some non-trivial code changes. The REGISTER handling code does not 
use any of the methods that exist in chan_sip to add message body 
content to its responses, it uses simpler methods that assume there 
won't be a message body.

In addition, this mechanism is really pretty broken anyway; the server 
would have to know where each phone is physically located in order to be 
able to provide the correct TZ value to it, and would have to be updated 
if the phone is moved. Not an ideal situation.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at www.digium.com & www.asterisk.org