Midrange and regional mobile operators are falling in numbers in the US, as the national players bolster their coverage and spectrum positions. The latest it Cincinnati Bell, which is exiting the wireless business and selling its spectrum to Verizon for $210m. Cincinnati Bell will continue to offer wireline and IPTV services, and even electricity, to customers in its regions in Ohio, Kentucky and Indiana but has given up on a mobile business which has shrunk from a peak of almost 600,000 subscribers in 2008 to 340,000 at the end of last year. ‘It has become economically challenging for us to invest in our wireless business at the levels necessary to deliver best-in-class service to our customers,’ said CEO Ted Torbeck…