After landing at several smaller US carriers in April, Apple's iPhone is poised to make another round of expansion into regional markets later this month, according to MacRumors. As of the writing of this post, three wireless carriers, including Bluegrass Cellular of Kentucky, Golden State Cellular of California and Nex-Tech Wireless of Kansas, will start selling the iPhone 4S on May 18.

These regional operators will offer the iPhone for US$50 off Apple's retail price with the 16 GB model selling for US$149, the 32 GB for $249 and the 64 GB for $349. The trio will also sell the iPhone 4 for $49. All prices require a two-year customer agreement.