An Avaya customer we don't often do work for contacted us the other day asking to have an extra IP phone activated and for us to see why their cordless phone in the warehouse won't ring now.
I tried plugging in the phone, it got power and a network address but couldn't see the phone system. I had the greatest of difficulty in getting onto the network to see the phone system with my laptop. Referring to a past configuration file I found what the network address of the phone system was, set it my laptop to be in the same range and connected OK. Long story short, since we had last been there to install the cordless phone, a couple of IP phones and upgrade their data cabinet, they had upgraded their router and the network addresses had changed. The phones all had static addresses so they communicated with the phone system fine. The phone system also couldn't get to a Network Time Protocol server and as a result the clock was quite incorrect.
If updating your network addressing, please consider the impact on your phone system, because if the phones had not been set with static addresses here then they would not have been able to reach the phone system.
Turning to the cordless phone, I confirmed they could call out but not receive calls. Apparently the boss had been fiddling with it to try and get calls to forward externally. They have a procedure to forward externally from any IP phone but were unable to understand what they had written down when my tech explained it.
In testing, calls simply bounced to voicemail or busy tone if voicemail was turned off. There was nothing set on the handset that should cause this. Defaulting the handset only resulted in a change of colour scheme and language to German but no change in behaviour.
In checking Monitor, I noticed an odd message - 302 Temporarily Moved. When called the base station was rejecting the call with this message, causing the Avaya to bounce it to voicemail. The base was registered and nothing in the config could be causing this.
I could see what it was doing but had no idea why it was doing it. We have many Gigaset handsets installed and none have ever done this before. The last straw to clutch at here was to factory default the base and reprogram. There are only a few settings to program up and it was probably safer to do that rather than reload a possibly corrupt configuration file. Once reprogrammed it worked perfectly.