The call flow is as follows:

(7960) --[SIP]--> (*) --[IAX2-trunk]--> (*) --[IAX2-trunk]--> (*) --[PRI]--> (PSTN)

TRUNKING:
===========================================================
    -- Executing Dial("SIP/cagny602-255f", "IAX2/m1m2/16462793676|60|r") in new stack
    -- Called m1m2/16462793676
 Tx-Frame Retry[000] -- OSeqno: 000 ISeqno: 000 Type: IAX     Subclass: NEW
    Timestamp: 00012ms  SCall: 16384  DCall: 00000 [216.128.80.41:4569]
    VERSION         : 2
    CALLED NUMBER   : 16462793676
    CALLING NUMBER  : cagny602
    CALLING NAME    : Test
    LANGUAGE        : en
    FORMAT          : 4
    CAPABILITY      : 268
    ADSICPE         : 2
    DATE TIME       : 146307833

Rx-Frame Retry[No] -- OSeqno: 000 ISeqno: 001 Type: IAX     Subclass: AUTHREQ
    Timestamp: 00012ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
    AUTHMETHODS     : 2
    CHALLENGE       : 172927922
    USERNAME        : m1m2

 Tx-Frame Retry[000] -- OSeqno: 001 ISeqno: 001 Type: IAX     Subclass: AUTHREP
    Timestamp: 00144ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
    MD5 RESULT      : 8304d174b3e5e660219e811834fb56ea

Rx-Frame Retry[No] -- OSeqno: 001 ISeqno: 002 Type: IAX     Subclass: ACCEPT
    Timestamp: 00145ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
    FORMAT          : 4

     -- Call accepted by 216.128.80.41 (format ULAW)
     -- Format for call is ULAW
 Tx-Frame Retry[-01] -- OSeqno: 002 ISeqno: 002 Type: IAX     Subclass: ACK
    Timestamp: 00145ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 002 ISeqno: 002 Type: CONTROL Subclass: (255?)
    Timestamp: 00148ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 002 ISeqno: 003 Type: IAX     Subclass: ACK
    Timestamp: 00148ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 003 ISeqno: 002 Type: CONTROL Subclass: (255?)
    Timestamp: 00151ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 002 ISeqno: 004 Type: IAX     Subclass: ACK
    Timestamp: 00151ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 004 ISeqno: 002 Type: VOICE   Subclass: 4
    Timestamp: 00166ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 002 ISeqno: 005 Type: IAX     Subclass: ACK
    Timestamp: 00166ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 005 ISeqno: 002 Type: CONTROL Subclass: RINGING
    Timestamp: 01649ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 002 ISeqno: 006 Type: IAX     Subclass: ACK
    Timestamp: 01649ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
    -- IAX2[m1m2]/16384 is ringing
Tx-Frame Retry[000] -- OSeqno: 002 ISeqno: 006 Type: IAX     Subclass: LAGRQ
   Timestamp: 10017ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 006 ISeqno: 003 Type: IAX     Subclass: LAGRQ
   Timestamp: 10016ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Tx-Frame Retry[-01] -- OSeqno: 003 ISeqno: 007 Type: IAX     Subclass: ACK
    Timestamp: 10016ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 006 ISeqno: 003 Type: IAX     Subclass: ACK
    Timestamp: 10017ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 007 ISeqno: 003 Type: IAX     Subclass: LAGRP
   Timestamp: 10017ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 003 ISeqno: 008 Type: IAX     Subclass: ACK
    Timestamp: 10017ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 008 ISeqno: 003 Type: CONTROL Subclass: (255?)
   Timestamp: 14689ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 003 ISeqno: 009 Type: IAX     Subclass: ACK
    Timestamp: 14689ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 009 ISeqno: 003 Type: CONTROL Subclass: ANSWER
    Timestamp: 14709ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 003 ISeqno: 010 Type: IAX     Subclass: ACK
    Timestamp: 14709ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Tx-Frame Retry[000] -- OSeqno: 003 ISeqno: 010 Type: IAX     Subclass: PING
   Timestamp: 20014ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
 Tx-Frame Retry[000] -- OSeqno: 004 ISeqno: 010 Type: IAX     Subclass: LAGRQ
    Timestamp: 20017ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 010 ISeqno: 004 Type: IAX     Subclass: ACK
   Timestamp: 20014ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 010 ISeqno: 005 Type: IAX     Subclass: ACK
    Timestamp: 20017ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 010 ISeqno: 005 Type: IAX     Subclass: PONG
    Timestamp: 20014ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 005 ISeqno: 011 Type: IAX     Subclass: ACK
    Timestamp: 20014ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 011 ISeqno: 005 Type: IAX     Subclass: LAGRP
    Timestamp: 20017ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Tx-Frame Retry[-01] -- OSeqno: 005 ISeqno: 012 Type: IAX     Subclass: ACK
   Timestamp: 20017ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 012 ISeqno: 005 Type: IAX     Subclass: PING
   Timestamp: 20015ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Tx-Frame Retry[000] -- OSeqno: 005 ISeqno: 013 Type: IAX     Subclass: PONG
    Timestamp: 20015ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 013 ISeqno: 005 Type: IAX     Subclass: LAGRQ
    Timestamp: 20018ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Tx-Frame Retry[-01] -- OSeqno: 005 ISeqno: 014 Type: IAX     Subclass: ACK
    Timestamp: 20018ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 013 ISeqno: 006 Type: IAX     Subclass: ACK
   Timestamp: 20015ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
    -- Hungup 'IAX2[m1m2]/16384'
   == Spawn extension (default, 16462793676, 1) exited non-zero on 'SIP/cagny602-255f'
Tx-Frame Retry[000] -- OSeqno: 006 ISeqno: 014 Type: IAX     Subclass: HANGUP
    Timestamp: 26984ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 014 ISeqno: 007 Type: IAX     Subclass: ACK
    Timestamp: 26984ms  SCall: 16384  DCall: 16384 [216.128.80.41:4569]

NO TRUNKING:
===========================================================
    -- Executing Dial("SIP/cagny602-bb40", "IAX2/m1m2/16462793676|60|r") in new stack
     -- Called m1m2/16462793676
Tx-Frame Retry[000] -- OSeqno: 000 ISeqno: 000 Type: IAX     Subclass: NEW
    Timestamp: 00011ms  SCall: 00002  DCall: 00000 [216.128.80.41:4569]
   VERSION         : 2
    CALLED NUMBER   : 16462793676
    CALLING NUMBER  : cagny602
    CALLING NAME    : Test
    LANGUAGE        : en
    FORMAT          : 4
   CAPABILITY      : 268
    ADSICPE         : 2
    DATE TIME       : 146308130
Rx-Frame Retry[No] -- OSeqno: 000 ISeqno: 001 Type: IAX     Subclass: AUTHREQ
   Timestamp: 00008ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
    AUTHMETHODS     : 2
   CHALLENGE       : 353795726
    USERNAME        : m1m2

Tx-Frame Retry[000] -- OSeqno: 001 ISeqno: 001 Type: IAX     Subclass: AUTHREP
    Timestamp: 00144ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
    MD5 RESULT      : fcdcb9e5b6027d8061e5a9c5ff7954c0

Rx-Frame Retry[No] -- OSeqno: 001 ISeqno: 002 Type: IAX     Subclass: ACCEPT
   Timestamp: 00140ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
    FORMAT          : 4
     -- Call accepted by 216.128.80.41 (format ULAW)
     -- Format for call is ULAW
Tx-Frame Retry[-01] -- OSeqno: 002 ISeqno: 002 Type: IAX     Subclass: ACK
    Timestamp: 00140ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 002 ISeqno: 002 Type: CONTROL Subclass: (255?)
   Timestamp: 00143ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 002 ISeqno: 003 Type: IAX     Subclass: ACK
   Timestamp: 00143ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 003 ISeqno: 002 Type: CONTROL Subclass: (255?)
   Timestamp: 00146ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 002 ISeqno: 004 Type: IAX     Subclass: ACK
   Timestamp: 00146ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 004 ISeqno: 002 Type: VOICE   Subclass: 4
   Timestamp: 00161ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 002 ISeqno: 005 Type: IAX     Subclass: ACK
   Timestamp: 00161ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 005 ISeqno: 002 Type: CONTROL Subclass: RINGING
   Timestamp: 01744ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 002 ISeqno: 006 Type: IAX     Subclass: ACK
   Timestamp: 01744ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
    -- IAX2[m1m2]/2 is ringing
Tx-Frame Retry[000] -- OSeqno: 002 ISeqno: 006 Type: IAX     Subclass: LAGRQ
   Timestamp: 10014ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 006 ISeqno: 003 Type: IAX     Subclass: ACK
   Timestamp: 10014ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 006 ISeqno: 003 Type: IAX     Subclass: LAGRQ
   Timestamp: 10011ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 003 ISeqno: 007 Type: IAX     Subclass: ACK
   Timestamp: 10011ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 007 ISeqno: 003 Type: IAX     Subclass: LAGRP
   Timestamp: 10014ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 003 ISeqno: 008 Type: IAX     Subclass: ACK
   Timestamp: 10014ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Tx-Frame Retry[000] -- OSeqno: 003 ISeqno: 008 Type: IAX     Subclass: LAGRP
    Timestamp: 10011ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 008 ISeqno: 004 Type: IAX     Subclass: ACK
   Timestamp: 10011ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 008 ISeqno: 004 Type: CONTROL Subclass: (255?)
   Timestamp: 12524ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 004 ISeqno: 009 Type: IAX     Subclass: ACK
    Timestamp: 12524ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 009 ISeqno: 004 Type: CONTROL Subclass: ANSWER
   Timestamp: 12527ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 004 ISeqno: 010 Type: IAX     Subclass: ACK
   Timestamp: 12527ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
    -- IAX2[m1m2]/2 answered SIP/cagny602-bb40
Tx-Frame Retry[000] -- OSeqno: 004 ISeqno: 010 Type: VOICE   Subclass: 4
   Timestamp: 13014ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 010 ISeqno: 005 Type: IAX     Subclass: ACK
   Timestamp: 13014ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
Rx-Frame Retry[No] -- OSeqno: 010 ISeqno: 005 Type: IAX     Subclass: HANGUP
   Timestamp: 19607ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
 Tx-Frame Retry[-01] -- OSeqno: 005 ISeqno: 011 Type: IAX     Subclass: ACK
    Timestamp: 19607ms  SCall: 00002  DCall: 00002 [216.128.80.41:4569]
    -- Hungup 'IAX2[m1m2]/2'
   == Spawn extension (default, 16462793676, 1) exited non-zero on 'SIP/cagny602-bb40'