I'm talking about taking the sim card out of your cellular modem and inserting it in your n900 thus achieving an internet connection, but having no cellular telephony (am i making sense here?).
wait, so you're telling me i can take the sim card that came with the modem and put it in my phone?
Sorry, ive just never heard of anyone doing anything like that, so i want to make sure i got it right..
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.
ahh.. That's a good point, i hadn't thought of that.
Anyway, just knowing the option is there is good enough, where anyone takes it from there is another issue.