The frequencies are coded into each individual handset. i.e. channel 23 on one unit may not be the same as channel 23 on another. The only way to find out would be to use a frequency counter/sniffer to detect the frequency.
Hello Bravo24, The Motorola HT600e transmitter is programmable by pc. Get the original cable programming and software and you will see that frequencies are allocated to each channel. You also can make changes in frequencies and programming in general. It's a good economic investment.
You can find it and get on alibaba.com and other pages related to communications equipment. For these cases, Mr. Google is a great assistant.
If on the business frequency you need to speak to the supplier NOT legal to use some of the ex job radios in UK and you would need a OFFCOM licence any way.
(May be an ex police radio not re programmed )