OK, first off I don't wanna hear crap like "They use all the towers" I know different straight talk phones use different towers. Some are on verizon, some are on sprint etc.
I'm hoping it runs on verizon as at least two out of the 4 of the other straight talk smart-phones use sprint. (the other lg optimus and one of the samsungs)

This is the only one I've found that actually says verizon
http://www.ebay.com/itm/LG-LS660-OPTIMUS-VERIZON-GOOD-QUALITY-Black-/280875203155?pt=Cell_Phones&hash=item4165777a53#ht _1489wt_1037

I can't find a straight answer across the web, it's all just a mention of sprint, a couple comments on it using both verizon and sprint somehow. So please SHOW YOUR WORK. Or some sort of proof anyway. Thanks....