Pinnacle may ask you to "factory reset" your phone to resolve problems - bellow are the steps:
NOTE: This process takes about 4-5 minutes to complete, and during this time, your computer may go offline temporarily if it is plugged directly into the telephone.
Press and hold down the ‘OK’ button on the phone (located in the center of the arrow buttons) for 5-10 seconds, or until the “Reset to factory settings?” prompt appears.
Press ‘OK’ on the phone or on the screen in order to reset the phone.
The reboot process that follows should take about 2-3 minutes to completely reboot twice.
If prompted, enter the last 5 digits of the serial number (SN). This is located on a sticker on the bottom of your phone. Note: the serial number will only contain numbers, not letters.
Enter these numbers with your keypad. The phone will finish resetting itself afterward.