Someone

[sipgate-out]
exten => _3.,1,Dial(SIP/${EXTEN:1}@sipgate-out,10)
exten => _3.,2,Congestion
exten => _3.,3,Busy
exten => _3.,4,Hang

[isdn]
exten => _8.,1,Dial(misdn/2/${EXTEN:1)187711)
exten => _8.,2,Congestion
exten => _8.,3,Busy
exten => _8.,4,Hangup

[default]
include => sip
include => isdn
include => sipgate-out