BlackBerry 8830 W.E Invalid IMEI, what do I do?

Hi. I'm new to the blackberry and got a free 8830 from a friend some time ago that he found while cleaning out some offices. I tried the IMEI blacklist checker at Swappa, but checking all 3 numbers (ESN, IMEI, and the other one, cant remember its name) keeps coming up as invalid. I was hopeing to use this on a prepaid account here and, if possible, unlock it later on down the road when i go overseas

I dont really know much about the phone yet.

The Revelent numbers are:

ESN (found under battery) 0761569285
IMEI 359089.01.684214.0
ESN (dec) 07615659285
ESN (hex) 4ceef115

I'm not sure why there is a missmatch between the esn on the battery case and what it shows me under menu>options>status.

I'd like to get some use out of this phone. I'm pretty sure it wasn't a greay market or some other scam sale, as it does show a decent amount of wear and before i wiped it (forgot how i did it now) it did have old messages and other signs that it was used.

Can anyone help me out here?

He found it cleaning offices?
My guess is that it's not a "gray market" device,
but I suspect it might be a weeee bit "warm",
if you know what I mean.....
What carrier is it branded to, if branded at all....try them to see if they can activate for you/check numbers out...

Yeah, they (the company he works for) clean out business buildings for a real estate company. The company that had been in there went out of business. I brought it into a verizon affiliate and had them check - not stolen. I actually had to show the guy behind the counter how to pull up the revelent info. He then had to wait until the manager come over and showed him how to check.

Whats weird is after i updated the OS to 4.5 for a momment, it showed another IMEI number. then it rebooted for no reason. Now its back to the same one: 359089.01.684214.0...i checked the other
imei against imei.info and it also came up with a different check digit. maybe this bb is busted, i dunno

Still, any help you could offer would be most appreciated.