Blackberry 7230 Phone Function on TMobile

Hi all,

I just recently got a used 7230. Everything works well except
there's no way I could access the "phone function". I tried to
press the "phone button", but it didn't work.

I have a SIM card from T-mobile that only has "phone plan (no
internet)". It used to work fine with a Treo, and that's basically
what I wanna do, use a phone with PDA function (no email, or internet
is needed). Obviously the 7230 recognized the SIM card and gave me
good connection signal. However, it did mention "data connection
refused". My question is,
1. Can I used this 7230 only as a Phone?
2. Do you think it's the SIM card that prevents me from accessing the
phone function?

Thanks,

Andy