We have a Toshiba phone system in our office. I don’t know much about it, because it is run by the very capable @mattsix, but today I jumped and did a little troubleshooting.
The reoccurring issue we had, was that a remote phone would connect to the IPU, ring, but there would be no audio. We were testing with an Airport Extreme hooked up to a DSL modem and an IPT 201-SD hooked to that.
First, we found this thread. We checked the “NAT/No Peer to Peer ” settings and they seemed right. Then I cam across this post. Wait, what? There are different types of NAT? I did not know that. As soon as we moved the Airport Extreme out of the mix, and put in a D-Link gaming router, the audio started working.
I guess the Airport Extreme is using Symmetric NAT and the D-Link is using a more capable NAT.
Mystery solved? We shall see.
Update: I found this in the “Starta CIX General Description”
The Strata CIX supports the use of IP telephones that are behind NAT firewalls.
Symmetric — At this time these routers may cause unreliable service or cause unwanted symptoms. These routers are not compatible with Strata CIX and Strata Net IP configurations