We have a strange situation with a single remote office Mitel 5312 IP Phone which is connected via a site to site SonicWALL VPN to a Mitel 5000 system running v6.0.9.61. There is no issue/delay with the VPN as the connecting computer (passes through the 5312 phone) has no latency or delays and ping responses are good. When answering an inbound interoffice call (other side of VPN) or placing an interoffice call, the remote party cannot hear any audio for the first 3-5 seconds of the answered or placed call. However, audio can always be heard (downstream) from the remote office to the 5312 without delay. The opposite party simply can't hear the person using the 5312 IP phone for initial several seconds. After this, it works flawlessly with no latency or delay whatsoever. We have checked firewall settings and can't find anything that would be blocking it. Also tried resetting the VOIP phone and issue persists. I've seen a few others who have experienced this issue, but no clear solution as of yet. Any ideas?
Example:
1. Place call from 5312 IP to remote office: Person answers and is heard saying hello, 3-5 second delay, then other party can eventually hear you talking.
2. Receive call to 5312 IP from remote office: Call is answered at 5312, 3-5 second delay, then other party (caller) can eventually hear you talking.
