can I use a 3G sim in non-3G phone?

[snowball]

As title really....can I use an O2 3G sim in an unlocked Nokia 6300, which is not a 3G phone?

[M@rtin]

It should be fine, it's only 3 that stop you from doing this as it costs them money if you're always using 2G.

[MC Rubber Chicken]

no you can't not in all phones anyway.... some phones only work with a gsm sim (older models) if you doubt me try putting a 3g sim into a nokia 6230 (not the i just the normal 6230)