would the Nexus S unlocked that is posted on ebay from at&t but unlocked will work here in the Philippines?

The i9020A from at&t has the following band(850 / 1900 / 2100 MHz UMTS)
telecommunication company here supply the following frequency band( 900/1800/2100 umits)

SO will the nexus s from at&t unlocked work here?
(will the gsm and 3G will work and can i send message (sms) using the gsm only?)