have bought the T42. unfortunately, these have no codes and our kids (for whom it was intended as a walkie talkie) can hear some strangers in the vicinity. this is disturbing. According to the information, the T62 devices have 8 or even 16 channels and 121 subcodes. my question: can i assume that i have (simplified) 16 frequencies x 121 subcodes at my disposal for communication, on which i will not hear anyone, unless the transmitter has also set exactly this configuration? i.e. just under 2'000? additional question: regarding 121 subcodes: are these CTCSS channels (or PL for motorola)?