Call forward at isdn operator side


I’m supporting small office PBX running on Asterisk. We have 4 incoming ISND lines, linked together, lot of incoming numbers and some office SIP phones.
There is dialplan written in ael. Everything work fine! External numbers are linked to internal, everting ok.

But now I need forward incoming calls to mobile phone. And employees need to set up/cancel forwarding from its office phones.
Solution like … forwarding is not acceptable because two lines are ocupied druing call and ANI display our office number, not custumer number.

Our isdn provider offer call forward at his PBX. But i don’t know how to activate it form asterisks.

Please help!

You need to use ECT (Explicit Call Transfer). How this could be implemented depends on the technology You’re using for connecting to ISDN - the commands/configurations differ from DAHDI,CAPI.mISDN a.s.o. up to ISDN-Gateways like Patton which may be used …

I have read about ECT. I’m using DAHDI with Asterisk
and ISDN controller: Cologne Chip Designs GmbH ISDN network Controller [HFC-4S] (rev 01)

I tried command DAHDISendCallreroutingFacility - no errors, but no redirecting also…
I tried capiCD - " No application ‘capiCD’ for extension "


In This case deflecting should work like in the following example:

exten => deflect,1,Proceeding() exten => deflect,n,DAHDISendCallreroutingFacility(${DESTINATION},${CALLERID(num)},cfu) exten => deflect,n,Wait(5) exten => deflect,n,Hangup()

where ${DESTINATION} is the destination number where the call should be transfered to
cfu indicates that the call transfer is unconditional

Note: DAHDISendCallreroutingFacility only works when the call is not answered yet by asterisk. The Proceeding() is necessary in front of DAHDISendCallreroutingFacility, and Your ISDN-provider must support ECT on the line.

And: If You’re using a Junghanns BRI-card You should probably use their special driver package for DAHDI (, this works at least for Asterisk 1.8.

I tried modify dialplan (add Proceeding() ), but no luck - just do not work…

I tried also tried to compile and install Junghanns modified DAHDI drivers, but there was errors.
My guess - Junghanns patch is old and don’t work on new dahdi_linux.
But DAHDI from debian repository works fine, except forwarding…
May be Lattelecom (our provider) don’t support ECT… But i know lot of companies, that use ISDN, some proprietary PBX and forwarding works just fine there…

I don’t have ideas anymore… ;(

If You want to compile the special junghanns-Drivers You just should use their original file (There’s dahdi 2.6.1 included).
As I already wrote: We work with this setup and the given dialplan-example succesfull (in our case at Swisscom-lines).

What You could do is trying to debug the ISDN-Line. Probably there may be some errors visible in the communication of the S0-bus to the provider.