[Serusers] SER Contact rewrite for Softswitch

Harry Behrens Harry.Behrens at dai-labor.de
Thu Oct 23 17:27:05 CEST 2003


Hello,

we have the following setup in our "Unified Messaging lab":

SUAs <-> LAN <-> SER <-> Softswitch <-> PSTN

The SER is provisioned as a SIP Server (essentially a SUA) from the Softswich point of view.

We have provisioned a number block of 20 numbers (from a 30-channel ISDN PRI) for direct inward dialling (DID) to the SER.
E.g. 12345620-12345639 are routed to the SER.

On the SER we have a number of users <user>@dai-labor.de, where the first 20 users have an alias
of 123456[23][0-9]
Each user also has his number added to his permanent contacts to enable (on the cheap) a "call by PSTN if not online" poliy.

The aim obviously being to have a 1-1 mapping between URI and allocated telephone number (we are still in the proof-of-concept phase and will move to DNS and ENUM based architecture at a later stage).

Scenario 1: OK
 PSTN user Up calls 12345621 - which is mapped to harry at dai-labor.de.
 If harry at dai-labor.de is registered, his SIP UA rings and the call is established.

Scenario 2: problem
 harry at dai-labor.de wants to use his UA to place a call through the Softswitch.
 The Softswitch "authenticates" (if you can call this authentication ;-( by looking at the 
 Contact header and comparing it to its database of numbers assigned to provisioned SIP Servers.
 I therefore need to be able to specify a rewrite of the Contact header to 
 replace harry@<Contact IP:port> with 12345621@<Contact IP:port>
 when the callee is of the form <number>@<whatever>

I am aware that this would be strictly speaking not proxy but rather B2BUA behaviour, but would still be
interested to know whether anyone has a solution to this problem or whether we need to hack one ourselves.

Many thanks in advance,

	Harry

Dr. Harry Behrens
Projektleitung BIB3R
DAI Labor - Technische Universität Berlin
Sekretariat GOR 1-1, Franklinstrasse 28/29, 10587 Berlin 

Fon: +49 30 314 23383
Fax: +49 30 314 21799

Email: harry.behrens at dai-labor.de

http://www.dai-labor.de

 




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