One mobile giant moves out while another moves in to fill the need for a faster connection. Cellular One will discontinue service and AT&T will take over its seven stores across the state. Cellular One representatives say the company can't afford to upgrade its Montana network to 4G technology. They say Cellular One customers will receive a $100 credit and pay no activation fees if they switch to AT&T. Verizon and AT&T are Montana's largest wireless companies.