What do you mean exactly when saying "I realized that I don't have a simcard in my Verizon phone" doesn't it need a simcard in order to work?
Is it some kind of special phone supplied only by Verizon that doesn't require a simcard?
If that's the case, then you problably won't be able to make the Treo 650 work with Verizon, it's a Tmobile device too right. If you want to use that phone you'll have to go with Tmobile, or you could go and have your sim lock removed so you can get it to work with other providers.
Good luck,
Marcus