1. PRI include 3 layers, before we can make a call through PRI, we need to make sure first two layer work normally. Layer 1 indicate physical connection while layer 2 indicate the synchronization between MyPBX and the E1 provider.
2. Debug commands under asterisk CLI:
under asterisk CLI, you can check layer 1 with command:
dahdi show status
Description Alarms IRQ bpviol CRC4 Fra Codi Options LBO
RED 0 0 0 CCS AMI YEL 0 db
OK 0 0 0 CCS AMI YEL 0 db
OK means layer 1 connected successfully. RED means disconnected.
under asterisk CLI, you can check layer 2 with command:
pri show spans
PRI span 1/0: Provisioned, Up, Active
PRI span 2/0: Provisioned, Down, Active
Up means layer 2 synchronize correctly, Down means synchronize fail.
pri set debug 2 span 2：Turn on PRI debug for span 2
pri set debug off span 2：Turn off PRI debug for span 2
The logs print in via ssh with debug on during the incoming calls are very helpful.