Introduction

Here, the approach to the problem of "cracking during ISDN trunk calls"

Common Cause is a difference between the ISDN clock between multiple connected ISDN lines on one PCI card.

• To get in contact with the ISDN provider with an explicit reference to clocking problems can bring relief.
• Optimally, all connections to the customers should be connected to the same PCI card.
• Alternatively, change the order of ISDN connections.

Sirrix-cards

Check the log file:/var/log/asterisk/full:
[Jul 31 09:37:44] DEBUG[3669] System.cpp: updating sync port
[Jul 31 09:37:44] DEBUG[3669] System.cpp: keeping sync port 2002
[Jul 31 09:37:45] DEBUG[3669] System.cpp: updating sync port
[Jul 31 09:37:45] DEBUG[3669] System.cpp: keeping sync port 2001
[Jul 31 09:37:45] DEBUG[3669] System.cpp: updating sync port
[Jul 31 09:37:45] DEBUG[3669] System.cpp: keeping sync port 2002
[Jul 31 09:37:45] DEBUG[3669] System.cpp: updating sync port
[Jul 31 09:37:45] DEBUG[3669] System.cpp: keeping sync port 2002
[Jul 31 09:37:45] DEBUG[3669] System.cpp: updating sync port
[Jul 31 09:37:45] DEBUG[3669] System.cpp: keeping sync port 2002

Digium-cards:

Important is to connect the first line to port 1 and then port 2, 3, 4 ...

Check the log file /var/log/messages:
Feb 24 04:02:09 localhost kernel: printk: 9 messages suppressed.
Feb 24 04:02:09 localhost kernel: wcb4xxp 0000:04:08.0: new card sync source: port 4
Feb 24 04:02:14 localhost kernel: printk: 9 messages suppressed.
Feb 24 04:02:14 localhost kernel: wcb4xxp 0000:04:08.0: new card sync source: port 4
Feb 24 04:02:19 localhost kernel: printk: 9 messages suppressed.
Feb 24 04:02:19 localhost kernel: wcb4xxp 0000:04:08.0: new card sync source: port 4
Feb 24 04:02:24 localhost kernel: printk: 9 messages suppressed.
Feb 24 04:02:24 localhost kernel: wcb4xxp 0000:04:08.0: new card sync source: port 4
Feb 24 04:02:29 localhost kernel: printk: 9 messages suppressed.
Feb 24 04:02:29 localhost kernel: wcb4xxp 0000:04:08.0: new card sync source: port 1
Feb 24 04:02:34 localhost kernel: printk: 7 messages suppressed.
Feb 24 04:02:34 localhost kernel: wcb4xxp 0000:04:08.0: new card sync source: port 4
Feb 24 04:02:39 localhost kernel: printk: 9 messages suppressed.
Feb 24 04:02:39 localhost kernel: wcb4xxp 0000:04:08.0: new card sync source: port 4
Feb 24 04:02:44 localhost kernel: printk: 9 messages suppressed.
Feb 24 04:02:44 localhost kernel: wcb4xxp 0000:04:08.0: new card sync source: port 4
Feb 24 04:02:49 localhost kernel: printk: 9 messages suppressed.
Feb 24 04:02:49 localhost kernel: wcb4xxp 0000:04:08.0: new card sync source: port 4
Feb 24 04:02:54 localhost kernel: printk: 9 messages suppressed.
Feb 24 04:02:54 localhost kernel: wcb4xxp 0000:04:08.0: new card sync source: port 4