I own a Yaesu FT-8900, and if you have an FT-8900, FT-8800, or FT-60, you know it’s very easy to accidentally enable the WIRES X Internet mode by brushing against one of the buttons. The Yaesu Wires X system is an Internet based linking system that doesn’t get much use here in the U.S, but is supported by most Yaesu VHF/UHF radios.
You probably have heard someone who has accidentally done this on their radio. When they key up, you hear a short DTMF tone, then no audio, then they sound normal for the rest of the transmission. You generally lose the first 3 or 4 words of their transmission. With this mode enabled, the radio sends out a DTMF digit at the beginning of every transmission. Most repeaters automatically mute the audio when they hear DTMF tones, cutting off the user. The person making the transmission generally has no idea this is happening other than a small, easy to miss indication on their display.
Fortunately, there’s a way to completely disable this so it won’t send the annoying tone over the air, and inadvertently cut off your transmissions.
Check out this PDF from K0NR for instructions for some of the common models.
After performing the above steps, it’s still possible to activate the Wires Internet mode, but it will not send tones over the air and mute your audio!