...Verizon historically needed Cellular South in MS because Verizon didn't have much of a network here (as good as T-mobile, at best). However, in the last two or three years, they bought both Alltel and Rural Wireless, which gave them 850 MHz spectrum* in about 85% of MS. Once Verizon gets those two networks fully integrated together, they may not need Cellular South as much as Cellular South needs them, and the dynamics of the relationship may change drastically.
*-Wireless 101: There's two main frequency bands in use for wireless at present, 850 MHz and 1900 MHz. The 850 MHz, being at a lower frequency, will transmit farther than the 1900 MHz. There are only two 850 MHz licenses available in each market, so whoever has those two licenses will typically have better coverage than those who do not. In MS, Verizon has about 85% of the A-band 850 MHz spectrum across the state, and the B-band 850 spectrum is nearly evenly divided between Cellular South and AT&T, with Cellular South having Starkville/Columbus, Oxford, the Delta, and most of South MS, while AT&T has central MS, all of I-20, I-55 from Hazlehurst to Oakland, the four counties nearest Memphis, and most of northeast MS.