Protocols and standards. We live and die by them, and while we can’t live without them, sometimes they can be a royal PITA. And so it is apparently, with Polycom’s interpretation of RFC4568 Session Description Protocol (SDP), with which I became all too familiar this week.
I was called in to try and figure out why a customer’s Polycom VVX’s intermittently couldn’t call out to the PSTN. They could place the call seemingly OK, but as soon as the external party answered it dropped.
Incoming calls were fine, and none of their other clients had any outgoing problems: their Office 2013 and Office 2016 PC clients were fine, as were the fading old CX600’s. Making this scenario all the more interesting is that the PSTN Gateways are NET / Sonus “VX 1200” gateways still running flawlessly from their Lync 2010 days – and still supported by the vendor until the end of 2018 BTW!
Media Bypass is enabled in this environment, so the obvious conclusion to draw was that we were dealing some some kind of incompatibility between the new-ish phones and the (ahem) “mature” VX’s.
