VOIP multiple lines problem

[Fire&Blood]

@Mods: Was debating where to start this thread, if I chose wrong I apologize, please move.


I have a intermittent yet daily occurring problem with VOIP. We have 4 lines at work. About 2-3 times a day, a scenario occurs in which worker A has a ongoing conversation with a outside business party, worker B dials out but as soon as worker B picks up the earpiece, (or dials without) he instantly "hijacks" the worker A conversation. Once it occurs, worker B cannot transfer the call back to worker A, the only way for worker A to continue the interrupted conversation is to physically attend to worker B's phone. It appears to occur randomly with any of possible A B C D worker combination. The number of lines in use appears to have no impact on odds of the problem occurring, so far I am unable to reproduce the problem and I can't identify any kind of trigger for this event either.

 

[kevnich2]

You are going to need to provide a lot more information than you did. What voip system are you running? Is this hosted voip or on premise? Are you using a pri or sip trunk? What phones are you using? Are employees at the same location or remote locations? Do other calls work ok with transferring, parking and picking them up?

 

[robmurphy]

If the calls are over SIP this screams lack of bandwidth.

It may be the link is also used for data and some one is uploading or downloading when this happens.

Could be router issue as well. For small routers turn off the SIP ALG.

Rob.

 

[imagoon]

This can also indicate the router has some sort of SIP "helper" or Gateway that is not managing packets correctly when the second phone tries to start a connection to the provider.

 

[Cooky]

This sounds like a configuration error.
If sound quality is the issue, then it's QoS / bandwidth related.
When head sets hijack conversations, it's definitely something else.
Have the vendor double check the config.

 

[alkemyst]

Definitely more info needed and ultimately the configs. Either you picked a crappy solution or a good one is configured wrong/has a failure.

 

[drebo]

Sounds like a misbehaving ALG. Nothing else will ever have that sort of effect. That's not the way SIP and RTP work.

Of course, we're going on the assumption that his trunk lines are SIP. He hasn't stated whether or not the SIP server is external or internal to the network.

Either that or the users are morons and the second user is actually barging into the call somehow.

 

[Fire&Blood]

I was trying to gather more info about our setup even before I started the thread, I figured it would be needed for diagnosing/troubleshooting but still haven't heard back from our remote IT guy.
I know little about VOIP, can't identify the setup myself. the 4 phones are identical, Grandstream GXP2000 http://www.grandstream.com/index.php/products/ip-voice-telephony/enterprise-ip-phones/gxp2000

Not sure if it's relevant, internet is via a local cable company, a Charter business line. I know this isn't the info I need to post, just wanted to chime in while I wait for a response. Thanks for the questions posted, I forwarded those as well.