@whoolly said in Switchvox phone issues:

Vendor insisted he has never had any VOIP issues with Sonicwall and didn't want to budge on that.

Even while it doesn't work. So you know that he'll say this to other customers now, even after this one. Chances are, he's had problems at all customers. SonicWall is culprit #1 for VoIP issues. I mean that literally. I get a call that someone has VoIP audio issues, my first question is always "Do you have a SonicWall?" Nine times out of ten, the answer is yes and nine times out of those ten, the SW was the issue. It's nearly a sure bet with audio issues.

Had you led this question purely with "I have these audio issues..." we'd have said "I bet you have a SonicWall."