An issue we are facing with our new VOIP environment - we use a cloud-hosted VoIP solution and Yealink T23 handsets behind SonicWALL NSA2600 firewalls. SonicWALL certified engineer has confirmed the correct ports for UDP and RTP are open and working.
Whilst we have sufficient bandwidth band and experience no packet loss/jitter we have issues where a handset will randomly disconnect after anything from 2 or 3 to in excess of 15-20 minute calls. Seems to occur with greater frequency on conference calls.
Normally a user will only notice when a call disconnects but we have noticed this happens even when the handset is not in use. Handsets are a mix of DHCP and static IP - both suffer from this issue.
Any help here as I'm starting to lose the will to live with this...