[Asterisk-Users] Problem with call drops

[Waldo Rubinstein]

Hello guys,

I've been having a a recurring problem with people complaining about  
calls being dropped.

I have 3 asterisk servers:

Gateway: running Asterisk 1.2rc2 with TE410P connected to 4 T1s of  
the PSTN
Server 1: running Asterisk 1.2rc2 with ztdummy using Gateway to  
access the PSTN (in/out)
Server 2: running Asterisk 1.0.9 with ztdummy using Gateway to access  
the PSTN (in/out)

I have agents connected to both Server 1 and Server 2.

The problem is that every once in a while, agents complain that their  
calls dropped. Sometimes it's some agents that complaint, some other  
times, ALL agents complaint at the same time.

When these complaints occur, the only thing I so is:

1) Issue a show channels on all three servers to see if there are any  
ongoing calls. I assume that if there are active calls, that not all  
calls dropped
2) Issue dmesg in Gateway to see if any of the T1s presented an alarm  
that could have dropped the calls

In either case, I don't see any errors in dmesg indicating there were  
problems with the T1s and I always see active calls in all the servers.

What can I do to further troubleshoot this? If I look at the CDR, how  
can I tell that a call was "abnormally" terminated? Are there any  
tools out there that would allow me to check the health status of the  
working system and not just the "availability" of the machines? I was  
looking at nagios but I don't know if it will do what I need to do.

The other thing I could think of is that there may be a network  
problem in the building. The way everything is connected is all  
agents are connected to a series of unmanaged switches in the "call  
center floor", which are daisy chained together and then one is  
connected to the main switch with a single cable drop. The main  
switch is where the Asterisk servers are connected. I figured that if  
one of the switches in the call center area fails, it could drop all  
calls or if there is a problem with the cable drop from the main  
switch, that could also affect all agents.

Any advise will be greatly appreciated.

Thanks,
Waldo