Subject: RE: [Sipping] refer and pstn

From: "Christer Holmberg (LMF)" <[email-masked]>
Date: Tue, 10 Jun 2003 16:38:42 +0200

Hi,

>>So, if you want to reproduce this with a pstn gateway, the incoming
>>pstn call can be automatically forward to the receptionist ip phone
>>by the pstn-gateway and then, the receptionist with the ip 
>>phone will transfer (refer) the incoming call from the pstn-gateway to another
>>sip UA in the company.  (kind of IP-PBX scenario).
> 
>that application is fine.  problems start when refer-to points to pstn
>destination.

Just to clarify. 

You said that the problem was that the calling PSTN user doesn't know he is being transfered, and/or he doesn't know where he's being transfered. Why is that problem different depending on if he is being transfered to another SIP user, or back to another PSTN user? 

Because there could be cases where there is no SIP signalling, if the MGC does a "local PSTN loopback"? In that case I guess it's more a signalling problem, and not a user problem (the user doesn't know where/when he's being transfered), right?

Regards,

Christer Holmberg
Ericsson Finland

> 
> -- juha
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_______________________________________________
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---

From: Juha Heinanen <[email-masked]>
Date: Tue, 10 Jun 2003 18:19:48 +0300

Christer Holmberg (LMF) writes:

 > You said that the problem was that the calling PSTN user doesn't know
 > he is being transfered, and/or he doesn't know where he's being
 > transfered. Why is that problem different depending on if he is being
 > transfered to another SIP user, or back to another PSTN user?

the problem is quite different from the operator's point of view who is
running the pstn gw.  if pstn gw gets a refer, it must somehow know that
the referred-by is not spoofed and that the referrer is allowed to
initiate a call to the refer-to number.

-- juha