Subject: RE: [Sipping] Associating SIP sessions with PSTN calls

From: "Michael O'Doherty" <[email-masked]>
Date: Thu, 19 Sep 2002 11:16:05 +0100

David,

I can see how we could use caller prefs to ensure that a call to a SIP
device associated with a PSTN call arrived at the right place (although in
this case we don't really need to do this) but I am not sure we can use the
approach to stop a SIP voice session call from some other user (who won't
have set any caller prefs and who will have used the same e.164 number to
address the SIP invite) reaching that same SIP device.

It is the same sort of concept but we want the callee to call the shots in
this scenario.

>> How do we indicate with an ENUM response that voice calls should go to
>> the PSTN number and other media/mixed media calls to a SIP device (one
>> .suggestion here was that if ENUM returns a tel URL as one of the options
>> for routing then that option MUST be used if the call is a voice call) ?
>>
>You don't. This is what caller prefs is for, right?

---

From: Paul Kyzivat <[email-masked]>
Date: Thu, 19 Sep 2002 21:59:13 -0400

> Michael O'Doherty wrote:
> 
> David,
> 
> I can see how we could use caller prefs to ensure that a call to a SIP device associated with a PSTN call arrived at the right place (although in this case we don't really need to do this) but I am not sure we can use the approach to stop a SIP voice session call from some other user (who won't have set any caller prefs and who will have used the same e.164 number to address the SIP invite) reaching that same SIP device.

No, you can't prevent it. But do you need to? Just arrange the sip device to refuse audio, and if that is the only medium offered in the call refuse the call. If a sip phone is calling, and enum gives multiple translations - one for the sip device and one for a pstn gateway - then at worst the call will be forked, and the gateway will be the only fork that succeeds.

As long as the sip device never claims to support audio you have no problem.

	Paul

> 
> It is the same sort of concept but we want the callee to call the shots in this scenario.
> 
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