BlackBerry Forums Support Community - HELP! Cant receive SMS messages!

:bb::bb::bb:

I originally had a Verizon blackberry phone. Then I unlocked it, gave it to my sister, but then at first when I tried to call her new ATT number, I couldn't. If I called from the phone to my house. The caller ID was my old number?. Even when I texted it was my old number even with her new SIM card in it. So then I tried playing around with mobile network options. I found a way, kind of. This is what I did

Manage connections> Mobile Network Options> Network Technology> GSM/UMTS

that made my phone go to ATT's network (finally). It says edge next to reception bars.

I tried calling my sisters new number, WORKED
sent a text, WORKED
I sent a text from my gmail to her new number, DIDNT WORK .

I don't know what to do? I researched this for a long time. I tried going to Host Routing Table> Register now
or I tried going to Mobile Network>Diagnostic Test

My results were
Blackberry Registration: Abort
Connected to Blackberry: Abort
Blackberry PIN-PIN: Abort

Someone PLEASE help me

Oh btw she had a different phone before I gave her my blackberry, everything worked. but once she put the SIM in th BB she can't RECEIVE text messages. only on the blackberry, but will work on hers.
I dont get wats the problem...