Passing caller number on call transfer


Following situation:
A calls B, B answers and transfers the call to C.
After the transfer, C can see B’s internal number on his display.

Is it possible to show A’s number on C’s display?

I know, i can manipulate the display contents with Set(CALLERID(…)=…), and this works on transfer, too. But, how do I know the original caller’s (A) number at this moment? (There is a second channel built for transferring, so I need to get this information from the first channel.)

If you need more information or examples, feel free to ask.

Thanks in advance!

This may differ between SIP and Dahdi. It may also differ between features and SIP transfers in SIP.

Asterisk doesn’t physically make a call from A to C for either SIP transfer mode and doesn’t, I believe, support the mechanisms (draft only?) for updating SIP CLIs.

Of course, if you use AMI, you can set the CLI before B calls C.


I believe you’re looking for the Connected line support that’s provided by Asterisk 1.8. See the CONNECTED_LINE channel variables.


There’s no dahdi, but both features and SIP transfers. Thought it is handled the same way in extensions.conf, but I have to recheck this.

Never used AMI before, so I’m not unhappy if it’s not required.

Seems to be what I’m looking for, but I can’t believe that such a thing hasn’t been implemented earlier. (We are running 1.6)
How do callcenters (and other companies in general) handle this???