[OpenSER-Users] RTP-Proxy

[Klaus Darilion]

Andreas Granig schrieb:
> Jerome,
> 
> In my opinion it depends on the policy of the VoIP provider rather than 
> on technical issues.
> 
> Proper implementation of RFC 4028 of all involved UACs might render RTP 
> analysis useless, if it's in line with the policy of the the VoIP 
> provider to have some minutes of tolerance in their CDRs in case of 
> missing BYEs (the tolerance can be controlled by the provider via the 
> defined headers). If that is still unacceptable by a provider, there 
> maybe should be some SIP/RTP-aware billing engines in place though.

Yes. If you do accounting for billing purpose, you should the accounting 
where the costs happen and were you have reliable CDRs.

E.g. if you have you  own PSTN gateway I recommend doing accounting on 
the gateway. The gateway always knows the SIP state and the RTP state. 
Further, the gateway should have RTP timeout and/or Session Timer 
support to detect dead sessions.

If do you not have your own PSTN gateway but use some PSTN gateway 
provider then you either trust the gateway provider and use the CDRs of 
the gateway provider or put a B2BUA between your SIP proxy and your 
gateway provider (thus the B2BUA is somehow a gateway to the PSTN 
provider) and do accounting on the B2BUA.

Doing accounting on the sIP proxy and RTP proxy works too if the gateway 
  can detect dead sessions - neverthless the CDRs wont be as accurate as 
the CDRs from the gateway.

Regarding accounting of SIP-to-SIP calls - if you do not bill them then 
you can use accounting on the SIP proxy for statistical reasons. if you 
want to bill them, the same as above applies.


regards
Klaus

> Andreas
> 
> Jerome Martin wrote:
>> On Thu, 2008-01-10 at 20:10 +0100, Iñaki Baz Castillo wrote:
>>> El Jueves, 10 de Enero de 2008, Jerome Martin escribió:
>>>
>>>> To summarize, I'd say that if you rely on RTP detection for billing,
>>>> then you have the following limitations :
>>>> - unreliable problem detection
>>>> - stuck with RTP proxying for ALL calls
>>>> - problems with VAD
>>>> - problems in corner cases with re INVITES changing the RTP stream
>>>> extremities
>>>>
>>>> What do you think ?
>>> I think that I should thank to you for a great explanation ;)
>> What, you're not even arguing ? :-) You're too kind. 
>> But seriously, this is a pretty hot subject, and I've never met anyone
>> suggesting the same as I did here, most of the time I hear the same
>> thing about rtpproxy + CDRs reliability.
>>
>> I'm sure some people are challenging what I wrote right now, in their
>> mind ! If we are lucky, we'll even get emails ! 
>>
>> Disclaimer: the above paragraph was not meant to start a flame war on
>> the topic between SST/pinging schools and RTP detection ones. At worst,
>> the two techniques can really complement each other.
>>
>> Regards,
> 
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