naja, die extension sieht ganz einfach aus
[default]
exten => _0.,1,Answer()
exten => _0.,2,Dial(SIP/${EXTEN}@sipgate_de_out,30,r)
exten => _0.,3,Hangup()
in der sip.conf:
[general]
context = unauthenticated
bindport = 5060
bindaddr = 0.0.0.0
srvlookup = yes
nat = force_report,comedia...