5.2 Trace

With tracing activated, the internal system messages (transmitted between processes), messages received on and sent to the PRI / VoIP ports, and AT commands and replies sent to GSM modules are written out. The listing of a message related to a specific call starts with the B-channel and GSM module numbers and an arrow showing the message direction. The right arrow (–>) means a message received on an interface (PRI, GSM, LAN) or a message directed from a lower layer process to a higher layer process (indication, confirmation). The left arrow (<–) designates a message sent to an interface (PRI, GSM, LAN) or a message directed from a lower layer process to a higher layer process (request, response). The message type (layer 3 messages are shifted by a space to the right, layer 4 messages by two spaces to the right) and the message content follow.

ISDN Messages

Typically Used ISDN Messages (Q.931)

  • !alertin – Alerting
  • !callproc – Call proceeding
  • !progress – Progress
  • !setup – Setup
  • !connect – Connect
  • !setack – Setup acknowledge
  • !connack – Connect acknowledge
  • !disconn – Disconnect
  • !restart – Restart
  • !release – Release
  • !restack – Restart acknowledge
  • !relcompl – Release complete
  • !facility – Facility
  • !notify – Notify
  • !stsenq – Status enquiry
  • !info – Information
  • !status – Status

Typically Used ISDN Elements - Cause (Q.850)

ID

Name

Whole name

1

Unassnumb

Unassigned number

6

Unaccchan

Channel unacceptable

16

Clear

Normal call clearing

17

Userbusy

User busy

21

Reject

Call rejected

27

Destout

Destination out of order

28

Invformat

Invalid number format

30

Stsenqresp

Response to StatusEnquiry

31

Normal

Normal, unspecified

34

Noanychan

No channel available

41

Tempfail

Temporary failure

42

Swcongest

Switching equipment congestion

44

Noreqchan

Requested channel not available

65

Nobearer

Bearer capability not implemented

81

Callref

Invalid call reference value

88

Dest

Incompatible destination

96

Elemmiss

Mandatory information element is missing

97

Message

Message type non-existent or unimplemented

99

Element

Information element / parameter non-existent or unimplemented

100

Elemerror

Invalid information element contents

101

Incmess

Message incompatible with call state

102

Timeout

Recovery on timer expiry

127

Undefined

Interworking, unspecified