Can you hear the scrambling going on? Since Verizon Wireless opened the floodgates with its $99 a month, unlimited flat rate calling plan, rival operators AT&T and T-Mobile quickly announced matching plans, with T-Mobile throwing in SMS and MMS as well. Now smaller carriers have joined the rush. Chicago-based U.S. Cellular, which has a customer base of six million customers in 26 states, and is the country’s sixth largest carrier, is offering a $99/month call plan, though for a limited time only (release). Jackson, Mississippi-based network Cellular South, trotted out an announcement saying they have had an unlimited flat rate plan since October of last year Moreover, its only $79 for regular cellphones, and $99 for smartphones. Both plans include text and data as well. The network, however, serves only Memphis, Mississippi, and coastal areas of Alabama and the Florida Panhandle.