The old thread may have been purged, as it only shows the first post (How do I determine if my BlackBerry is "unlocked
Boost is a possibility I have thought of, but Nextel will give me a lot more functionality.
I guess my biggest concern is that it is blocked/locked because of being lost or stolen... always a risk you take when you buy something used at a swapmeet. Now that I've been able to get into it, and get the phone number, I find that it's a San Diego number, so I may be able to find the previous owner. Time for a little Googling, I guess.
Thanks, Dubdub! Once again, I appreciate the help!