In the snippet below the Switchvox is receiving red alarms in System Status for the PRI connection. In this instance the Switchvox is sending outbound SABME messages as a connection attempt to the provider but not receiving anything back. This is most likely an issue with the provider or their on-premise equipment.
Time: 1299884940.632585
> Unnumbered frame:
> SAPI: 00 C/R: 0 EA: 0
> TEI: 000 EA: 1
> M3: 3 P/F: 1 M2: 3 11: 3 [ SABME (set asynchronous balanced mode extended) ]
> 0 bytes of data
Sending Set Asynchronous Balanced Mode Extended
localhost*CLI>
> [ 00 01 7f ]
localhost*CLI>
> Time: 1299884941.632579
> Unnumbered frame:
> SAPI: 00 C/R: 0 EA: 0
> TEI: 000 EA: 1
> M3: 3 P/F: 1 M2: 3 11: 3 [ SABME (set asynchronous balanced mode extended) ]
> 0 bytes of data
Sending Set Asynchronous Balanced Mode Extended
localhost*CLI>
> [ 00 01 7f ]
localhost*CLI>
> Time: 1299884942.632584
> Unnumbered frame:
> SAPI: 00 C/R: 0 EA: 0
> TEI: 000 EA: 1
> M3: 3 P/F: 1 M2: 3 11: 3 [ SABME (set asynchronous balanced mode extended) ]
> 0 bytes of data
Sending Set Asynchronous Balanced Mode Extended
localhost*CLI>
> [ 00 01 7f ]
localhost*CLI>
> Time: 1299884943.632596
> Unnumbered frame:
> SAPI: 00 C/R: 0 EA: 0
> TEI: 000 EA: 1
> M3: 3 P/F: 1 M2: 3 11: 3 [ SABME (set asynchronous balanced mode extended) ]
> 0 bytes of data
localhost*CLI>
The Switchvox is expected to see a UA (unnumbered acknowledgement) back from the provider. If we do not receive the UA we will continually send SAMBE's until such time. The Switchvox follows q.931ISDN protocol.