17 Feb
2012
17 Feb
'12
10:38 a.m.
On 02/17/2012 10:06 AM, Efelin Novak wrote:
Hi Alex,
thanks for the answer.
My customer is on the SIP side. So my customer sees a prefix of my
PSTN gateway in the contact header.
Oh, I see. So, the UA is your customer, and the prefix is added by
the proxy?
Sequential requests are being sent
to<prefix><number>@<gateway_ip>.
However I think when I remove the prefix from the contact, the
gateway would have no problem in responding to this seq. request
(Isn't the call defined by to_tag, from_tag, call_id?).
Well, no, that's not going to work. The call - depending on whether
you're referring to the dialog or the session - may indeed be defined
by those things, but the gateway is not going to accept a sequential
request to a target URI different than the one it asked for.
Having the proxy translate them back and forth statefully will cause
far more problems than it solves, and for that reason is not practical.
You're pretty much going to have to find a way to get the gateway to
not send the prefix in the contact. What kind of gateway is it? Most
gateways' translation features can be implemented at different stages
of call processing, e.g. pre-processing, post-processing. If you can
get it to strip the prefix off but store it for use as a routing guide
in an earlier stage (something more like pre-processing), it shouldn't
appear in the Contact.
--
Alex Balashov - Principal
Evariste Systems LLC
260 Peachtree Street NW
Suite 2200
Atlanta, GA 30303
Tel: +1-678-954-0670
Fax: +1-404-961-1892
Web: http://www.evaristesys.com/, http://www.alexbalashov.com/