Issue with Phone Power VOIP & Nortel System

I've been having an issue for over a week now. Phone Power tech support has been great but we haven't been able to solve the issue yet.

Here is my configuration:
FiOS Internet with brand new Westell 9100 wirless FiOS router from Verizon. The GrandStream is connected directly to the Westell. I have the annual plan so have a cloned line. Both lines are connected to our Nortel "Norstar" phone system.

This is what I understand of the issue after a week+ of troubleshooting with no solution yet:

The lines will work fine for long periods (1 or 2 hours)and then when you try to dial out you will get the fast busy signal after you've dialed in the # and are waiting to connect. It will happen intermittently with both line #1 and line #2 (the cloned line). Javier in tech support said that what's happening is that when it works the correctly ports 5060 and 5061 are being used. But when it doesn't work somehow data gets sent to ports in the 4000 range.

I put a regular phone into the GrandStream and switched between lines and it seemed to work OK (line #1 using 5060 and line #2 using 5061). I haven't tested it this way for a long period of time yet.

At first we were thinking it was the new Westell as we'd put the ports in the DMZ but it still happened. Then we wondered if the Nortel was causing an issue. Javier said that it seemed sometimes when you hung up a line and switched over to another quickly the grandstream didn't have time to realize the line had been terminated.

Last month I tested out VOIP on our Nortel system using my friend's Linksys phone router which had ACN VOIP service. That was one line and worked fine. That makes me believe maybe it's the GrandStream...

I'm hoping any of you techie guys can figure out this mystery. Thanks!

It is a little difficult to guess your exact problem from the information that you have given. Your Phone Power voip will be configure to best suit that service and you say that it is cloned... is it running on a different IP to you internet connection? It seems that you are getting some confusion with ports or IP addresses. Try giving the Grandstream a fixed local IP and then setting the Grandstream to use ports 5063 and 5064 UDP as well as 8000 - 8020 UDP and see that they are forwarded to the Grandstream IP from your router (or some port that your other phone system is NOT using).

Thanks for the advice. I'm going to try this on Monday.

Well, we tried your suggestion and unfortunately it didn't help.

The more we get into this I think it has something to do with how the Nortel system terminates calls. We seem to have the problem when we use a line, hang up, and then go back to use it within about 5 minutes I'd say. That's when it gives us the fast busy. If we didn;t use the line again for over roughly 5 minutes it seems to work fine again.

Hopefully this clue helps and you have another fix we can try.

Thanks!

So perhaps the next thing is to find out is whether or not the Grandstream detects that the call has ended and does not hang up or perhaps does not detect that the call ended and just times out due to inactivity. On the other hand, the fact that the Linksys router worked could still indicate port problems because the voip data transport is set up internally in that device.
Are you running STUN on the Grandstream?

I tested the GrandStream with a Panasonic 2-Line phone system today and no issues. So it does seem clear that the issue relates to the Nortel system. Somehow the GrandStream gets confused when the Nortel terminates a call.

I don't know about STUN but will ask the Phone Power tech guy who's helping me tomorrow. If you have anymore ideas I'd love to hear them.

STUN is set within the Grandstream web based setup. I can't tell you eactly where as you have not said what model you have. It might help but should not hurt to test it. The voipuser stun sever is stun.voipuser.org and that will do for testing.

Thanks for the additional info. The GrandStream is model# HT502.

The full manual for the ATA is here
http://www.grandstream.com/ht502.html

The use of STUN is described on p 16 and the voipuser server is stun.voipuser.org

Make sure that NAT traversal is turned on.


There is other useful information in the manual.