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Hi,
Thanks for the resoponses.
What if we dont have any gateway(or RTP Proxy) in between? Suppose a
proxy who is also responsible for billing is the only entity between SIP
UAs...
What is wrong if proxy/B2BUA sends OPTIONS to each party at regular
interval and if 200 OK is not received , disconnect the call and stop
billing? (Any way all SIP entity are suppose to support OPTIONS).
thanks and regards,
Sushil Kumar,
Axes Technologies (I) Pvt. ltd.
-------Original Message-------
Date: 03/18/04
19:40:57
Subject: RE:
[Sip-implementors] How to stop CDR?
wrote:
> One way with the currently existing standards is to run the call
trough a
> trusted UA of the billing entity. That entity can measure on the
RTP (or
> RTCP) level if the connection is still alive. Typically, this UA
will be
> a PSTN gateway or a B2BUA (back-to-back user agent).
Some media gateways (e.g. Cisco) have RTP media inactivity timers
and
will tear down a SIP session if RTP goes dead (which is generally
a
good idea). This (IMHO) all but solves the PSTN problem.
The SIP<->SIP problem is harder. But again, if you are running
an
RTP proxy, you could detect inactivity there and tear down the
SIP
session. This would also not be a bad idea for tearing down
failed
or one/way connections through NATs/firewalls now I come to
think
of it. Clearly that's only going to work for an RTP payload.
Beyond that, it would require a change to, or some innovative
(ab)use
of the SIP standard to effect some form of keepalive. But note
checking
SIP server still has IP connectivity to the UA does not check that
a
functional call is still in progress. It could be (for instance)
that
the remote end has disconnected, the RTP's dropped etc.
Alex |
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