The Connect Systems CS750 is, as was mentioned, geared toward HAM usage. It has the capacity for 2000 channels and 64K or so contacts. It also has some features that have been added to appeal to HAM users. The CS710 is now marketed toward commercial users although it was very popular with the HAM crowd and went by the Model CS700. It is an older model and has the capacity for 1000 channels and 1000 contacts. There may have been some changes to the 710 since the 750 came out but I'm not sure what they might be. Give Connect Systems a call. I deal with them quite regularly and find them very friendly and easy to do business with.