CloseCallAmerica is a reseller that acquired a company called TeleCommunications Systems, which acquired a company called Aether Systems that operated Blackberry by Aether. All of which is a long way of saying that Close Call users access BIS as follows:
https://bis.na.blackberry.com/html?brand=tcs
I believe that Close Call users are actually on the Verizon system (my device is a 7250).