I would listen for any repeater activity on the 8 GMRS pairs. It is easy to find the PL tone, by changing the tone and then transmit until you find it, listen for a delay or use another radio or scanner to listen for your voice, announce your calls signs and ask for permission. also depending on your area, check the list of repeaters here on www.MYGMRS.com, and ask for permission by e-mail. and yes you will need to program your radio for a +5000mhz offset and discover their PL tone so as to access. if they use an uncommon pair, they will be a little harder to work. You may consider running your own repeater, you can get a used one or a simple one made from 2 radios for a couple hundred bucks. if you don't mind running two separate antennas. if you prefer a single antenna install you will need a duplexer at another 100 bucks.