Hi. There are two versions of thr binatone 550 radios. The version with the time is an older modelm They do run on the same license free frequencies of PMR446. The first set is on channel 7 and the second is on channel 1. In order for all radios to communicate you have to press the menu key and the up and down arrows until they have the same channel (main digit) and subchannel (the smaller number) matched. All sets will then communicate. I do hope this helps.