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Community Member

Call Forwarding question

I have situation like this:

A -> B -> C

A - some phone from PSTN network

B - IP phone registered with Call Manager; it has call forward to C

C - mobile phone

Phone A calls B, and call is forwarded to C phone. When call goes from B to C, I see A number as calling and C number as called. Is it possible to have B number as calling and C number as called?


Hall of Fame Super Red

Re: Call Forwarding question

Hi Vlaho,

Have a look at this doc, it describes the method to change what number is shown on redirect (from Originating to Redirecting > in your case to change from A to B);

Failure to Forward Call Offsite - Issue with Calling Device Number

From this good tech note;

Hope this helps!


Hall of Fame Super Gold

Re: Call Forwarding question

Hi Rob,

you suggestion is right but this is strange if you think about it. To make the transfer, CCM places a new call to PSTN, apparently presents ANI of A, telco happily accepts it and deliver it to C as calling number ?!?

This means, the system can originate calls with arbitrary caller-id to (at least) cell-phones user. One malicious person could easily use caller-id as police number, or any other exploitation of this.

I'm not sure if this is know, understood and accepted by the all involved parties (telco, company, and telecommunication regulatory body).

Hall of Fame Super Red

Re: Call Forwarding question

Hi Paolo,

You are correct :) this is quite a gap! Most Telcos won't accept this non-billable number (thus the doc that I sent Vlaho) but many do. We do not allow Call Forward External so this has never been a problem for us, but this is something that, as Administrators,we need to keep an eye on.

Keep up the great work and take care!


Community Member

Re: Call Forwarding question

Hi Rob,

I didn't try to configure call forwarding as it was in document you send. The Telco has configured that C phone see gateway number of site. They are happy with that solution, so I leave that situation as it is.

Thanks for the document.

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