Got an unlocked treo 650... some issues

Well I just got an unlocked treo 650 for tmobile and I'm having some problems with it.

I insert my SIM card and it recognizes the network with no problems and I can make calls, but I can't seem to be able to receive calls or msgs .... they just wont go trough... I even tried calling my phone from another phone and it goes straight to the voicemail as if the phone was off... but the phone option on the treo is on the ON position.
Am I doing something wrong ? or missing something ?

Any help is greatly appreciated.

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› See More: Got an unlocked treo 650... some issues

Hello,
I am having the same issues but I am trying to use a TMobile sim on a Cingular Treo 650. What service do you use?