G1 without the data package?

I have had the G1 for a little over a year now and I have always had the data package. I find it way to expensive and the people I talk to the most have Verizon. In a week I am saying good riddance to T-Mobile and canceling my contract. A woman that I work with is wanting to buy my G1 from me and just put her SIM card in it instead of buying one from T-Mobile directly. She is wanting to avoid getting the data package so she will just put her SIM card in my G1 and use it. Will this work? A guy I work with used to work for T-Mobile and he said it should work but I want to see if anyone has done this successfully. He said she just wont be able to send or receive picture messages. And she isn't wanting to use the internet anyways so she wouldn't need the data package. We tried this out yesterday and she was able to receive calls but texts weren't working. It asked for me to log into my G1 account so I was thinking she might just have to create a gmail account. Any thoughts on this?