You may have set an Alert Tone for the FTO's programmed. There are 10 unique Alerts similar to Cell Phone Ringer Tones and 10 levels of Volume independent of master volume level. Set the Delay to INFINITE so you may hear the call after FTO. To resume FTO Standby, turn scroll knob after FTO.FM51 said:I also hear a strange tone go off from time to time with no voice before or after it. Any ideas?