New radio does not communicate with older model

I have an odd issue. I just purchased a new set of Motorola Talkabout T400 radios for the campsite. I have an older TALKABOUT MR350R set. I have set the T400 to the same channel as the older MR350R radios however when I try to send from the T400 to the MR350 nothing happens. If I start the communication first on the MR350 then everything works and all four radios communicate properly. The moment I shut down the T400 I have same issue again. I assumed the same brand and same channel would work however am I doing something wrong or is this a common issue with older versus newer radio

Sounds like one of the radios is configured to use a “privacy code” (sometimes referred to as a sub-channel). This will ignore any transmissions not generating a very low inaudible tone specific to that “code”.

Look for a number other than 0 (privacy code disabled on Motorola FRS radios) UNDER the channel number on the radio display. Setting both to 0 will allow them to hear any radio regardless of brand on that channel. Setting them both to a matching “privacy code” will also allow you to talk (and will still allow other brands so long as the tone is the same).

Remember, these aren’t really privacy codes. They simply ignore anyone using a different tone, or no tone. This can be useful on crowded channels, but you are still basically communicating out in the open :slight_smile:

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Always helps to read the owners manual before using any two way radio.

This is why I hear so many people in deer rifle season using 1 / 1 - because that was the factory default frequency that came on when they put the batteries in the radio… Even the roger beep shut off is beyond their abilities…

Whippurwhil is correct. These are the CTCSS tones and DCS codes. Motorola calls them interference eliminator codes. The easiest way to fix this is to turn off CTCSS tones and DCS codes on all four radios and test. Once the radios are able to communicate with one another, you can choose to assign a privacy code as needed. The important thing to remember is that if you set a tone or code to a channel, you must set the same code to the same channel on all four radios, or you will be back to square one.

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