Nokia N900 is compatibile with GSM and 3G network. you can set up Nokia N900 network for only GSM or 3G, or both GSM and 3G. the network settings on Nokia N900 is simple, just press the Menu icon > then go to Settings > scroll to and tap Phone > select Network mode then you will find 3G, GSM, Dual. if you select Dual, you will use your Nokia N900 with both GSM and 3G network.
if you want to select Nokia N900 network manually , just go to Settings > select Network selection > Manual > select the network you want > and Select.

Tags: Nokia N900 network compatibility, Nokia N900 network settings, Nokia N900 networks