Hello everyone. Let me first admit, that I'm a run of the mill Windows network administrator. Not a phone expert, so please be gentle.
Some time ago, we got a Peplink 300 load balancing device. We use it for DMZ'ing so we can put things outside our overkill protective firewall. It just so happens that our OfficeServ 7400 system is in this DMZ.
We have a VoIP phone. Whenever someone calls it, the phone rings, but when the call is picked up there's no sound. It's like both ends are muted. However the call is connected. Except for voice, everything works. VoIP person can put the call on hold, have a non-VoIP phone inside the office pick it up, and everything is fine.
Now here's the weird thing. Sometimes the VoIP phone works with voice. It's kinda hit or miss (user says it's like 1 out of 4 times). However even when a call like this works, it can suddenly go "voiceless" on both ends if either caller does something like, putting the call on hold.
We were thinking the problem is due to our Peplink doing load balancing with the calls. So we killed that part... however the problem still persists. Any advice?
On a side note: the Peplink has a special exception, that allows three custom SIP ports to be added into the device, if the service provider has custom ports. Currently still trying to get the port info from our provider, but I don't think it's anything exotic.
On the Peplink I see activity going over ports 6000 and 9000 for the VoIP user's IP address. Those ports are allowed through the device and firewall (plus all the others like 30000 to 30031).
But what are ports 6000 and 9000 doing exactly? I'm assuming that's the part that's working, and not voice related? Also what ports does the voice go over? I'm thinking 30000 to 30031... is that correct?
Thanks for any info.