From mISDN.org

Contents 1 Callforwarding with Keypad Elements 1.1 Call Forward in general (CFU) 1.2 Call Forward when busy (CFB) 1.3 Call Forward delayed (CFNR) 2 Call Forwarding with Facilities

Callforwarding with Keypad Elements

Since chan_misdn-0.3.1-rc31 you can modify the Callforwarding rules at your providers switch. To do that chan_misdn supports a channel Variable which is called MISDN_KEYPAD. In this variable you can encode special strings which modify the callforwarding rules in the switch. This is right now tested on German Telekom Switches.

A sample dialplan could look like:

exten => 551,1,Noop(Enable Callforward) 
exten => 551,2,Set(_MISDN_KEYPAD=*21*${TARGET}*${MSN}#)

exten => 551,1,Noop(Disable Callforward)
exten => 552,2,Set(_MISDN_KEYPAD=*#21#${TARGET}#)

exten => 551,1,Noop(Check Callforward)
exten => 553,2,Set(_MISDN_KEYPAD=#21#)

;send an empty Setup to port 1, the switch will read the keypad message
exten => _55X,3,Dial(mISDN/1/)

Call Forward in general (CFU)

activate: *21*<targetnr>*<msn>#
deactivate: #21*<msn># (or #21# for all msns)
check : *#21*<target>#

Call Forward when busy (CFB)

activate: *67*<targetnr>*<msn>#
deactivate: #67*<msn># (or #67# for all msns)
check : *#67*<target>#

Call Forward delayed (CFNR)

activate: *61*<targetnr>*<msn>#
deactivate: #61*<msn># (or #61# for all msns)
check : *#61*<target>#
change delay: *62*<seconds>#

Call Forwarding with Facilities

chan_misdn supports sending a Calldeflect Facility, during the Alerting phase, this will tell the Switch from the provider to reroute the call to the specified destination. you can do this with the follwing dialplan snippet:

;lets assume you want to forward the call from number 1111 to number 9999:
exten => 1111,1,Ringing
exten => 1111,n,Wait(1)
exten => 1111,n,misdn_facility(calldeflect|9999)
exten => 1111,n,Wait(3)
exten => 1111,n,hangup