Attention Vermont residents: AT&T will sell its mobile phones, including the Apple iPhone 3G, in your state beginning next Thursday.

AT&T, as of today the nation’s second-largest carrier after newly merged Verizon Wireless / Alltel, previously lacked spectrum and stores in the northern New England state.

That changed last month when AT&T and Verizon completed a spectrum swap.  After that, AT&T was able to put its name on 10 former Unicel stores, spokeswoman Kate MacKinnon explained.

AT&T’s 3G coverage expands nationwide except for Arkansas, North Dakota, South Dakota and Wyoming.  In those states the iPhone 3G reverts to 2G connections.

Separately, Verizon announced its own network expansion this week, also in Vermont.  Cell sites are being added areas near ski resorts in Killington and Stratton Mountain.