It worked fine until today. Only rings once and then disconnects. what can I do

Hope this helps!
The issue is that the control board requires reconfiguration.
Firstly switch off the appliance and disconnect from the mains.
Reconnect and Press and Hold the Minus key '-'
While holding the minus key press keys 1 through 4 in turn within 4 seconds. Each key press will give an audible beep.
Once done you should get a 'C' displayed for each ring element.
Now place a pan of water on one element. Press the Plus key '+' next to the element ring and wait for the 'C' to change to '-'.
Repeat that for each element and once complete the appliance will switch off.
Reconfiguration is now complete and you can use the appliance as normal.

Return it for warranty, if you fool with it you will void the factory warranty.

I would check the phone line itself. If it got pinched or partly disconnected that could cause it.

http://www.home-electronics.net/USER-GUIDES/29875_DOM_EN_AN_IB.pdf

Remember to also disconnect direct tv receivers. I had the same problem untill I unplugged them from the phone line.

When you call in, what happens? Does it ring once and disconnect? Are you able to answer and it disconnects?

Does this happen on all lines? Just inbound?

ME TOO

I would just disconnect or remove the ringer from the car. Under the dashboard. Listen until you locate it and remove it. They have a timing sensor that is suppose to turn off the ringer after a few seconds. It seems this timer has gone bad. if you replace the whole ringer circuit it may work. But if you have a fairly good memory to take out the key, you can just disconnect the ringer. But it is up to you.

dump the memory by deleting your mailbox and your call log-

I had the exact same problem and tried everything. It wasn't until I unplugged and main base from the electrical outlet for a few minutes and plugged it back in -- for some reason that made everything work. It is worth a try. We had some minor electrical outages in the last week due to weather so I assume that screwed something up.