Look at the lights on your phone modem, then follow the corresponding steps.
This usually means there is no backup battery, the battery is exhausted or the unit has not been plugged in.
If all the lights are flashing on the Internet and telephone modem, it may be picking up some interference from your house phone wiring.
If only the TEL light(s) on the front of the Internet and telephone modem are flashing, this means the modem sees the phone as 'In Use.'
If the above tips and tricks didn't work, sometimes resetting the Internet and telephone modem will re-establish communication once it has been lost.
Lastly, try resetting your modem online using the Modem Refresh tool in My Account.Reset Your Modem Online