Hi,
As you have somewhat found out it can only be AIM Buddies (Or rather US Phones via the AIM service).
The Computer has to be set to "be In" the United States (See th Language and Text pane in Lion or International in earlier OS versions.
The Phone then has to be on a Carrier that also takes the AIM SMS forwarding service.
Search the App store for SMS apps and Utilities
11:23 PM Friday; February 3, 2012
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Lion 10.7.3)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
"Limit the Logs to the Bits above Binary Images." No, Seriously