Subject: RE: [Sipping] refer to PSTN

From: "Stastny Richard" <[email-masked]>
Date: Wed, 17 Mar 2004 09:59:11 +0100

Juha

I have an order to write an ID regarding the enum dip indicator for the
tel: URI
in iptel

I could try to include the pstn indicator for tel: in this draft and
lets see how the reactions are ;-)

Richard

> -----Original Message-----
> From: Juha Heinanen [mailto:[email-masked]] 
> Sent: Tuesday, March 16, 2004 12:37 PM
> To: Stastny Richard
> Cc: Arunachalam Venkatraman; [email-masked]
> Subject: RE: [Sipping] refer to PSTN
> 
> 
> Stastny Richard writes:
> 
>  > If an indicator is required to force a call to the PSTN, 
> it should be  > independent from enum: eg tel:+xxx;pstn
> 
> this would be fine with me.  is someone writing an internet 
> draft describing the pstn uri parameter or does someone have 
> a better idea on how to solve the problem?
> 
> -- juha
> 

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---

From: "Stastny Richard" <[email-masked]>
Date: Thu, 18 Mar 2004 10:56:34 +0100

Hi folks,

From the discussion I see currently the following scenarios for ;pstn,
lets discuss it with the examples of a mobile number:

Assumption: UserB has an ENUM-entry (opt-in) for his existing mobile number
to sip:[email-masked]

Case A: UserB is registered with an IP-phone and has also a forwarding
active to his mobile phone (forking, dual ring). So if UserA is looking
up the mobile number in ENUM, the call is routed to the server of providerB
and to ring the mobile phone providerB sees the mobile number and has to
send an INVITE to a PSTN-Gateway with tel:+xxx;pstn (and not to do another
ENUM lookup for this number).
Advantage: userB may chose where he picks up the call
Disadvantage: UserB is paying if the call finally taken at the PSTN

Case B: UserB decides to redirect (e.g. he is not registered) and wants
to tell UserA to call the mobile phone on the PSTN, now userA needs to tell
his server NOT to do an ENUM-lookup, but directly route the call to the
PSTN, again with tel:+xxx;pstn.
Advantage userB: he is not paying
Disadvantage userA: he has to pay

Case C: User A knows that there is an ENUM-entry, but he wants to force
the call to the PSTN in the first place; again he has to send tel:+xxx;pstn
to his provider.
The (dis)advantages are the same like in case B

Regarding case B: the same may be achieved with the following
entries in ENUM:

IN NAPTR 100 10 "E2U+voice:sip" !...!sip:[email-masked]! .
IN NAPTR 100 11 "E2U+voice:tel" !...!tel:+xxx;pstn

So ;pstn may also be used in ENUM entries (which is not true for
the enum dip indicator.

Best regards
Richard

-----Ursprüngliche Nachricht-----
Von: Juha Heinanen [mailto:[email-masked]] 
Gesendet: Donnerstag, 18. März 2004 07:06
An: Christer Holmberg (JO/LMF)
Cc: Stastny Richard; Arunachalam Venkatraman; [email-masked]
Betreff: RE: [Sipping] refer to PSTN

Christer Holmberg (JO/LMF) writes:

 > Does this solution require that the redirection proxy, inserting the
 > "pstn indicator", knows that the call is initiated from PSTN in the
 > first place? 

the call does not need to be initiated from the pstn.

What would a normal SIP UA do if it received a 3xx response with the
indicator?  it would ask the user, would you like to try this other
destination and then send out the invite normally.

 > Also, if I have a SIP phone, and wants to divert my call to PSTN, the
 > phone would have to support the indicator too, to tell the
 > redirection proxy (or whatever database it uses) that the phone is in
 > the PSTN network...?

you would need to configure in the phone the redirection uri and that
would thus need to contain the ;pstn parameter.  i don't know what you
refer to by "phone" in the last sentence.

-- juha