Hi,
I'd also like to add my 2 cents to this topic, which might be slightly off-topic on this mailing list. Imho the problem discussed here is a major defficiency of the SIP protocol, which forces most vendors to implement proprietary extensions in their equipment. Call supervision is a feature that might not be important for best-effort services, but is of utmost importance when deploying SIP within a commercial environment.
Have a look at, e.g. H.323. They do have several redundant mechanisms to detect stale calls (e.g. at H.225 RAS level (IRQ/IRR/IACK/INAK), and at call signaling level (Status request/Status)). These messages offer detailed information on all ongoing calls within a terminal/gateway - either on sending an explicit request or by asking the endpoint to provide this information on a periodical base. Beside this, RRQ/RCF also provides re-registration features similar to REGISTER timers in SIP.
Again imho the clean solution for SIP was to have an equivalent of these features defined in the 3261 core. It's too late for this now. What still can (and should) be done is an RFC that defines an extension to SIP which implements call supervision.
Concluding: It's obvious that _real_ call supervision that is capable to detect malicious, non-standard compliant terminals (which, e.g. signal voice but send video over the voice channel) requires some border gateways featuring RTP content sniffing. But this is imho no excuse for SIP not providing standardized means capable to supervise calls on standard-compliant SIP devices.
regards --Joachim
-----Original Message----- From: users-bounces@openser.org [mailto:users-bounces@openser.org] On Behalf Of Bogdan-Andrei Iancu Sent: Donnerstag, 27. Oktober 2005 21:02 To: Daryl Sanders Cc: users@openser.org Subject: Re: [Serusers] Re: [Users] Detecting runaway calls
Daryl,
normally, a PSTN provider who offer quality service must offer a way to detect hanged calls. There is also a detection mechanism based on media (on GW) - at least CISCO GW have.
regards, bogdan
Daryl Sanders wrote:
This is exactly what I am trying to overcome. Do third party PSTN providers typically employ any other means of monitoring a call? I would think the would automatically disconnect the call
after a certain
amount of time if there was no media detected.
On 10/27/05, Iqbal iqbal@gigo.co.uk wrote:
problem with session timers, is if you have several
different routes
and you dont control all the end gateways....then its a pain, so I would think you would need a plan B, just in case to ensure
you double
checked, but agree with bogdan, b2bua i great but I think
the overhead
is not needed.
Iqbal
Bogdan-Andrei Iancu wrote:
Hi Greg,
that's the fortunate case of having already a B2BUA on the path :). But only for this particular case, I find the usage of a B2BUA a little bit to "heavy"....
Session Timer is actually doing a great job ;)
regards, bogdan
Greg Fausak wrote:
The re-INVITEs definitely work. I run some setups with Jasomi inline (a commercial inline b2bua). I configure them to
reINVITE,
works like a charm. If the reINVITE isn't answered (in either direction) the Jasomi sends BYEs in both directions. I believe other commercial gear works that way.
Also, I believe Session-Timers are supported by Cisco
gateways, but
I don't have experience with those.
-g
On 10/27/05, Daryl Sanders daryl.sanders@gmail.com wrote:
Thanks for the info guys! It sounds like I need to do a little reading up on cseq to determine if this will even work,
or find a
PSTN gateway provider that supports Session-Timers.
- Daryl
On 10/27/05, Bogdan-Andrei Iancu bogdan@voice-system.ro wrote:
>by sending re-INVITEs from the middle of the path you will >increase the cseq number differently on each side...so you will >need to synchronize the cseq value when some in-the-dialog >requests are passing through your proxy....and that's quite >complicated.... > >regards, >bogdan > >Daryl Sanders wrote: > > > > > >>Would it be possible to fake a REINVITE then check the
response
>>to determine if a call is still in session? Just
brainstorming...
>> >>- Daryl >> >>
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