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

   -- Executing Dial("mISDN/1-u1", "SIP/0@sipgate-out|10") in new stack
    -- Called 0@sipgate-out
    -- Got SIP response 482 "Loop Detected (no match)" back from 217.10.79.9
    -- Now forwarding mISDN/1-u1 to 'Local/0@sipgate-out' (thanks to SIP/sipgate-out-a6e3)
Dec  4 23:17:16 NOTICE[6422]: chan_local.c:479 local_alloc: No such extension/context 0@sipgate-out creating local channel
Dec  4 23:17:16 NOTICE[6422]: app_dial.c:479 wait_for_answer: Unable to create local channel for call forward to 'Local/0@sipgate-out' (cause = 0)
  == Everyone is busy/congested at this time (1:0/0/1)
    -- Executing Congestion("mISDN/1-u1", "") in new stack
  == Spawn extension (default, 308003301000, 2) exited non-zero on 'mISDN/1-u1'