Random, quick half rings on R200 Voip

R200 4.3.1R1

We are trying to figure out why one of our customer's phones is ringing, only a half ring, then stopping every 30 minutes (not sure how exact this is, customer said on the 20 and 50 minute mark just about). We have changed IP address, extension, firewall rules are in place. There is nothing in the logs (which are set to debug) that seem to correlate with those times.

We have other VOIP customers and have not seen this before. 

Any suggestions?


What is the local wiring like - one phone jacked into the R200, or jumpered to existing in-wall wiring?  If the latter, is the connection to the old copper line provider unplugged from that wiring?


A single phone was connected. We are thinking it was toll fraud. We had them set up with their extension equal to their phone number. Changing the extension to a different extension number seemed to fix it.

Thanks for the response,


We found the customer had tons of voicemails on her line, and after deleting those, the rings stopped. Her phone model has a feature that alerts for present voicemails, which she brought with her from her old house. At her old house, she had voicemail disabled, and had never heard the phone do that before.

So, we then disabled her voicemail on this phone, and the ringing stopped! She had been blaming us for weeks, and was too embarrassed to call us back letting it know it was fixed. We followed up anyway, and all is good in the world.