CO trunk stays in in-service/active state without connected port

[gandra]

Hi,

We have S8400/G650 system running CM 3.1.2 with patch 12396. There is ISDN-PRI and 3 CO lines connected. User has explicitly requested that the existing CO lines have to continue working.

We have the following problem:

after some time (nothing regularly – sometimes it takes shorter, sometimes longer) those CO trunks stay in
in-service/active state without connected port. To someone calling those numbers from outside lines appear busy (if it is called from a fixed line) or there is Error in connection message (if the call is made from cellular). We have to perform busyout/release on those trunk groups to make them available to calls.

Those 3 CO lines are put in different trunk groups that are incoming only. We restricted those trunk groups from calling each other or other trunk groups on associated COR (though there’s enabled trunk-to-trunk transfer on whole system). We also disabled flash transfer on analog phones.


Has anybody had similar problem? Does anyone have any idea what can cause this problem?


Thanks in advance,

 

[ken07734]

are these co lines loop or ground?

 

[gandra]

All CO trunks are loop-start.

 

[telnettech]

there is your problem.....it is recommended that CO trunks connected to a PBX be ground start.......what is happening is either the PBX or the CO is not detecting the drop in loop current to disconnect the call....I would recommend working with Telco and changing them to ground and you will see this disappear

To error is human.....if the machine doesnt work, then KICK IT !!!!!!!!!!!!!

 

[ken07734]

try turning on disconnect supervision, it might help.....