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)