Angel Watch supports GSM devices and is fully unlocked with worldwide compatibiliy.
As long as you're not using a CDMA carrier like Verizon or Cingular (USA only), your watch should work.
Give us a call or email us at support@angelwatchco.com and we'll help you out.
USA: +1 888 787 4757 8am-7pm MST Mon-Fri, Sat 9-3 pm
UK: +44 808 189 2762 8am-7pm GMT Mon-Fri, Sat 9-3 pm