[OpenSIPS-Users] Removing a VIA line required by Telco.

[Jeff Pyle]

David,

Opensips is a proxy.  A proxy's role is dictated by RFC3261.  It's fast,
lightweight, very scalable, and has some very nice features you're already
taking advantages of.  But, it's still only a proxy.  A proxy needs Via
lines.  Period.  To otherwise manipulate the traffic or keep state in other
ways turns it into something it's not.

Iñaki's right.  You need to find a new telco.  The fact they don't permit
proxies illustrates they really don't understand what they're getting into
with SIP, and sooner or later you're going to encounter something they can't
fix.  Or, if they do know what they're doing, their business model is
certainly not friendly towards your goals.  But that's a discussion for
another place and time.

One fact remains -- you will not be able to use any proxy as you're looking
to with your current telco.


- Jeff



On 4/20/09 3:48 PM, "David Gilbert" <openser at dclg.ca> wrote:

> Jeff Pyle wrote:
>> David,
>> 
>> As I understand it, a SIP proxy needs the Via lines to properly route.  It
>> sounds like in your case you need to move Asterisk (or any B2BUA) forward in
>> your diagram to be the entity that communicates with your telco.  No Via
>> lines, no proxy.  A B2BUA, however, by design hides the topology of the
>> network behind it.  No extra Via lines.  Other SBC-class products do that as
>> well but probably aren't worth the potential cost.
>> 
>> Or, find a telco that sucks less.  Unfortunately that doesn't sound like a
>> possibility.
>> 
>>   
> That's our current fallback position.  The issue is complex.  We're
> using the OpenSIPS proxy for two reasons: a) reliability (it's in a
> configuration with CARP and other fancy stuff)... and b) to divide
> billing.  The issue is that we "receive" multiple PRI with different
> parameters from the Telco and they require that be on a different IP for
> each one.  OpenSIPS makes that fairly easy.  Asterisk will only talk to
> one IP per installation (requiring multiple machines or virtualization).
> 
> Can't OpenSIPS be smart and remember the other VIA line as part of the
> "state" it keeps?  I know that the solution we replaced (run by another
> company) used a switch that didn't handle the media and yet still
> managed to deliver only one VIA line to this telco.
>