[SIPForum-discussion] SIP original A-number

[Jonathan Wagner]

The problem is the PBX must send that information in the INVITE. Typically
this does not happen as the PBX "loops" the call through the box and the new
call leg is in fact a NEW call leg and will look as such in the INVITE. If
the PBX can make use of the ISDN Redirected Number IE, this can be converted
to either a Diversion header or History-Info header to tell the Application
Server that the call belongs to the proper user and the "correct" CLID is
displayed.
Some PBX's simply send the call back out then change the outgoing INVITE to
be From A-Number To forwarding destination, many Application Servers will
reject this call because neither the A-number nor the forwarding destination
are users built on that server and the call appears to be invalid.

So to answer your question, yes there are ways to preserve the A-number in a
SIP message, the PBX/IAD/SBC must present this information in the SIP
message.

Jonathan Wagner

On Wed, Aug 27, 2008 at 10:54 AM, Jimmy Svensson <Jimmy.Svensson at tdc.se>wrote:

>  Hi!
>
> Is there any features in SIP to enable show original A-number? Any special
> fields that can be used?
>
> We as an operator use SIP-trunking to connect enterprise PBXes and see a
> demand to display the original A-number when doing an external forwarding.
> In this case someone calls an extension in the PBX that is forwarded to an
> external number. A new call leg is created to call this external number,
> here I want the original A-number to be shows as From but this is not
> allowed because of A-number-validation in our application server.
>
> Any good solutions/workarounds?
> Thanks!
>
>
> *Jimmy Svensson**
> *Network Engineer
> Technology Planning
>
> TDC Sverige AB
> Box 799
> SE-191 27 SOLLENTUNA
> Tel +46 8 563 101 23 dir.
> Tel +46 8 519 810 00 vxl.
> Mobil +46 701 81 01 23
> Email jimmy.svensson at tdc.se
> Web tdc.se
>
>
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