The following was adapted from an old magazine article (unknown source; please let me know if you know, anyone).
1. To Start:
• Is the problem system-wide or just one phone?
• If system-wide, check the phone system cabinet’s AC plug or the circuit breaker.
2. Phone Problems:
• Is your handset plugged in? Make sure that the handset cord is plugged into the handset and the base, and also that the connection between the phone base and wall jack is secure ...