[OpenSIPS-Users] [NEW] SDP codec manipulation feature

[Iñaki Baz Castillo]

2009/7/28 Bogdan-Andrei Iancu <bogdan at voice-system.ro>:
> The codec related ops are very "light" and suitable for a proxy, in the way
> that the proxy influence the codec negotiations, but without bringing the
> SDP negotiation into an inconsistent state. This is the reason why there is
> no "add_codec" operation (even if it is perfectly possible), but only
> "delete" and "swap priorities" were implemented - because only these ops do
> make sense from proxy pov.
>
> Let's consider some typical cases:
>
> 1) you can a PSTN termination with a wholesale provider and you know that he
> provides a poor GSM codec, so you can simple remove GSM as advertise codec
> (from your customer's calls) and to offer a better quality (via G729, G711,
> etc).
>
> 2) you, as a SIP provider, handle media on your platform (media relaying or
> media services) and you want to force your customers to use G719 over G711
> to avoid bandwidth exhaustion. So you  can change and set a higher priority
> for G719 over G711 in the SDP offer.
>
> IMHO, both cases are perfectly applicable for a proxy.

Ok, if it works well nothing to say :)




>> I wonder what would occur in the following cases:
>>
>> - The UAC/UAS use encrypted SDP (S/MIME...).
>> - The UAC/UAS use multipart content (some devices do it for an INVITE).
>>
>
> I can raise the same exceptions for the media relaying, or for whatever
> other functionality that require access to body.

True.



> I have to disagree with you here. OpenSIPS does not want to become a B2BUA -
> this is totally false. It started as a SIP proxy and it will never stop
> offering this  functionality with 0 penalties. But honestly speaking a
> simple proxy is not able to offer all the functionalities required by the
> SIP providers (more complex scenarios, more control over the traffic, etc).
> Aside the simple proxy engine,  OpenSIPS added support for dialogs (even if
> it is still a proxy and not B2BUA) to give you more power in building
> services. In the same manner, the SDP support was added and also in the same
> idea the B2BUA support will be added.

Ok, let give it a chance :)



-- 
Iñaki Baz Castillo
<ibc at aliax.net>