You can create a custom extension files under /etc/asterisk/ombutel called extensions__50-cisco.conf and paste the following dialplan
[cos-all-custom](+)
; Enable/Disable call-forwarding
exten => _cfwdall-.,1,Answer()
same => n,Goto(cos-all-init,${EXTEN:8},1)
same => n,Hangup(normal_clearing)
The phone make a call to x-cisco-serviceuri-cfwdall-XXX where XXX is replaced by the feature number, in this case *60
After save the file, remember to reload asterisk dialplan:
asterisk -rx"dialplan reload"
