three mobile broadband sim in a phone

My understanding is that three's mobile broadband gives full internet
access where as the broadband add on gives restricted access. And, the
two different services use different sims.
If this is correct, what service would you get from putting a three PAYG
mobile broadband sim into a phone with HSDPA (such as the HTC P3600),
would it be able to make and receive calls, or just transmit data?
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DavidM newsNO@SPAMdjmorgan.org.uk
www.djmorgan.org.uk