Silent external callers, vendor/telco/network mgr deny problem

[mawhin]

Hi all,

In short, I'm the network manager from the subject. Since about the time we changed ISDN providers, we've been getting problems.

We've two 3300 ICP's, each with an ISDN bearer, on different subnets on a routed IP network. Which isn't at all full. Promise.

Intermittently, but relatively frequently ( 1 call in 10 when it's bad ), on calls that come in on the bearer connected to ICP(a), that are routed using ACD? ( the caller gets to press 1 ) to handsets homed on ICP(b), we get the following...

Our operator answers, but cannot hear the caller. I've a capture off the network of the RTP streams, and the incoming stream is good packet-wise, but is all zeros. i.e. not quiet, but silent. These calls cannot be picked up by members of the pickup group. 'Good' calls can.

I can't find anything wrong with the network. I've sniffed ICP(a) and the handset on both good and bad calls, and the RTP stuff (I can't decipher the MiNET stuff) is just as good on both. Our mitel vendor has looked at the ICPs, and we've power cycled them, the ISDN vendor has had BT test the bearers. We all agree it's not a problem with our stuff. One of us is wrong.

Any thoughts?

BTW, I know I'm light on important detail, that's cos I'm pretty green here. I'm the network guy. We've tried to get training, but the vendor's not really interested.

I'm sort of after a list of things that might cause this, in lay-geek language. I'd like some hypotheses, and hints as to how I might test them.

 

[gomaze]

There could be a couple of reasons for the one way adiao that you are having.

The fist few things I would look at are the timers. There is a good help file on what timers to take a look at and you can find it by searching Call Overflow.

The second would be if your agents are using headsets. We had this problem of agents using Plantronics brand amps with the headsets. The users that ran on batteries would have this issue as the amp would go into sleep mode and would take about 15 seconds to wake up once on a call. The caller would be able to hear the agent but not the other way around.

Hope this helps.