2.5 miles is more like 13,200 feet (2.5 x 5,280) than 1350 feet. At 9,152 feet, the best AT&T could offer me was 3.0 Mb/s; it is doubtful they could do as well with 4,000 feet more.
I posted this speed/distance chart in jeffkrol
's topic as well:
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New Fusion average speed/distance chartThis shows speed v. distance for ADSL2+. When I switched from AT&T to Sonic.net, I received an ADSL2+ modem. I played with the old ADSL modem (Siemens SS4100) and the new ADSL2+ modem (ZTE 831II). At 9,156 feet, either would sync at ~5600 kb/s, max.
You can try and dicker for an upgrade at the same $20 price point, but you won't get more than the Express tier at your distance. What you will get is IPDSL service, which replaces ATM with PTM, and PPPoE with 802.1x. ATM+PPPoE incurs a 15% overhead "penalty"; so figure 0.85xsync (0.85x1536=1305.6), or 1.3 Mb/s maximum download speed. PTM+802.1x only incurs a 4% overhead "penalty"; so 0.96xsync (0.96x1536=1474.56), or 1.4 Mb/s down.
Only you know if that measly improvement is worth the trouble. Also consider: At some future date you will receive something like a 45-day notice that ADSL is going away. When that happens, you can either accept U-verse Internet service, or switch to some other service.
You might check with Sonic.net to see if they offer Fusion service out of SNMACA11. If they do, they also offer bonded pair (at 2x the price), which would effectively double your speed. But still ATM, so still 0.85xsync.