12 Feb
2019
12 Feb
'19
6:57 p.m.
Hi Filippos,
Kamailio can indeed modify many aspects of a SIP message, though the
devil is in the details.
https://kamailio.org/docs/modules/5.2.x/modules/textops.html
https://kamailio.org/docs/modules/5.2.x/modules/textopsx.html
Many message attributes are exposed through "pseudovariables":
https://www.kamailio.org/wiki/cookbooks/5.2.x/pseudovariables
A handful of which (such as $ru) are mutable.
Headers can be accessed on a read-only basis through the $hdr()
pseudovariable:
https://www.kamailio.org/wiki/cookbooks/5.2.x/pseudovariables#hdr_name_-_he…
There are, of course, formal limits to what headers and attributes a
proxy is allowed to modify, by virtue of being in series to the same
logical SIP call leg in and out. Even then, Kamailio has some elaborate
contrivances for working around this in clever ways:
https://kamailio.org/docs/modules/5.2.x/modules/uac.html
"Business logic to figure out what action to take with a SIP request"
probably describes most useful applications of Kamailio. It wouldn't
have much viability as infrastructure if it did not have that
capability.
-- Alex
On Tue, Feb 12, 2019 at 05:00:20PM +0100, Filippos Vasilakis wrote:
Hi,
First of all I would like to congratulate and thank everyone who has worked
in Kamailio. It looks like an awesome tool.
I am starting a side project and I am not very familiar with Kamailio
although I know SIP and VoIP in general, so I am more looking for answers
that tell me if it's possible or not what I am asking along with some hints
on how/where to look.
Is there a way to filter/forward/modify(through the headers) incoming SIP
requests and Kamailio SIP responses programmatically in Kamailio ? I have
seen that you can run embedded code like Ruby, but I wonder if this is for
simple things or more complex stuff which probably is in my case since
there will be plenty of business logic to figure out what action to take
with a SIP request. I have also found the EVAPI that is supposed to be
handle events through TCP but not much more info available.
So to sum up, is there a way to filter/forward/modify incoming SIP requests
and create responses programmatically in Kamailio ? If yes, what's the
proper way of doing that ? If no, any idea where I should look for that?
Thanks,
Filippos
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--
Alex Balashov | Principal | Evariste Systems LLC
Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/