The vast majority of the time this is caused by a simple programming mistake when the Site ID Phrase is changed by the user. The byte of memory that tells the microprocessor what type of RFC-1 hardware it is controlling immediately follows the Site ID Phrase in memory. Very often this byte is accidently changed while programming the Site ID. The way to avoid this is to press the * key to exit the programming mode as soon as you are done with your changes so that no other memory locations are altered. The way to fix it is to reprogram the value 1 at address 0996.

Here is the procedure step by step. Enter the keystrokes in bold type.

1. Go online with the RFC-1/B from the local phone
2. Enter the programming mode: 80
3. The RFC-1/B will prompt for the advanced programming security code: 4150
4. The RFC-1/B will prompt for a four digit address: 0996
5. The RFC-1/B will repeat the address and wait for a command
6. Enter the correct value and press the pound key (#): 1#
7. Exit the programming mode by pressing the star (*) key: *
8. Disconnect from the RFC-1/B and hang up: 99