It should work fine, but it slightly depends on your network, so the only way to be certain is to try it. You should be aware of a couple of caveats though - firstly you might lose out on more than voice - at least Vodafone UK PAYG data dongle SIMs don't support SMS, and secondly you'll need a decent 3G data connection for VOIP, whereas with a normal SIM you'd be able to get a working voice call even in areas with nothing better than a weak basic GSM signal.