Identifying forwarded calls based on DID

Posted on 2010-04-05
Medium Priority
Last Modified: 2013-12-21
A client has multiple DID that are forward to his cell phone via extensions.conf (exten => 3032223333,1,Dial(SIP/3032224444@provider).  When he receives the calls he will like to know which DID is the call is coming from.

I tried to mess with the Caller ID, perhaps adding a number prefix to identify the DID’s
exten => 3032223333,1,Answer
exten => 3032223333,n,Set(CALLERID(num)=2${CALLERID(num)})
exten => 3032223333,1,Dial(SIP/3032224444@provider)

But in the cell phone I receive an “Unknown Number” or “Unavailable”

Is there a way to work around this? Identifying the DID that is forwarding the call and keeping the Caller ID

Question by:larrytous
LVL 36

Expert Comment

ID: 29899630
No you cant set the CallerID to a number that you dont own. Even without any modification to the callerID the original number will try to be preserved and then rejected as it is not yours.
The only thing I think you can do is to set the callerID to the exact DID number the call came in on.
LVL 25

Expert Comment

by:Ron Malmstead
ID: 29921117
I disagree with grblades on "can't set the callerid to a number you don't own".... because the truth is, it "depends" on your provider.

MOST sip providers will not allow you to control your own callerid number.  (name is never allowed to be controlled by you, attempts to set it sometimes results in rejected calls as well).

However, on most PRI line providers, and a few sip providers, you can set your callerid NUMBER only.

That being said... you are also trying to set the CID as 11 digits rather than 10
exten => 3032223333,n,Set(CALLERID(num)=2${CALLERID(num)})

Just make it...
exten => 3032223333,n,Set(CALLERID(num)=${EXTEN})

...if that doesn't work, contact your provider, and ask them what level of control you have on your own callerid.
LVL 25

Expert Comment

by:Ron Malmstead
ID: 29921332
The trade off is that you don't see the number that is calling...but rather the number they called in on.
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LVL 10

Expert Comment

ID: 30120973
You can do what you are asking but you have to be running SIP, you have to have a router OS that supports Sip redirect headers and the carrier you are using supports it.

Accepted Solution

cwhall earned 2000 total points
ID: 30130659
We tried the same thing and had issues where some mobile carriers would strip off the preceding digit, or send nothing all together, even if you could control the caller id.

You can have a message played to the called user indicating that it is a forwarded call and then he can determine which number the call came in on with something like: Dial(ZAP/g1/${EXTEN},A(call-from-DID-1))

The "call-from-DID-1" would be the recording to play. You can use digits if you don't feel like making a recording.

Author Comment

ID: 30625487

Very elegant solution! Thank you.

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