Hi all. New here and not really a phone expert so your patience is appreciated!
We have a Mitel 3300, connected to an MBG, which has been giving us problems in recent weeks. When speaking with external users (both landline and mobile, on both incoming and outgoing calls) we are experiencing issues with our audio dropping out part way through the call. We can still hear the external people fine, they just cannot hear us. This can happen 30 seconds into a call, or 15 minutes into a call. It seems to be happening at random and none of the servers seem to show any errors (no dropped packets for example).
Here is the main issue - just before Christmas we had to segregate our network into several Vlans, and put two of the Vlans behind an additional firewall. Logically, I've been assuming that this change has been the reason behind the issues (we had no issues prior to this). However, as I understand it, issues with one-way audio is usually down to the firewall not being configured properly to allow the correct traffic inbound and outbound. This isn't the case at the moment as I have now allowed all traffic from out telephony Vlan (and servers) without any rules being applied. If the issue was with the Vlans and routing problems, I would expect that to manifest itself as calls simply not being able to be made, not for the call to connect and work fine, but then cut off after several minutes.
I've tried everything I can think of but I'm definitely not a VoIP expert so I know there is probably lots I've not tried. I've set QoS settings on all the switches to make sure bandwidth isn't an issue, though as the audio can drop out when there is virtually no-one in the office, I doubt that is the problem. As mentioned, I've basically turned off all firewall rules for the telephony equipment to make sure the firewall isn't in the way, though again, if the firewall was an issue I wouldn't expect the calls to connect and then the audio drop off.
Any ideas or suggestions people could throw my way would be much appreciated. As I said, I'm certainly not a VoIP expect so I'll try to answer any questions as best I can.
