Switch to Straight Talk from Verizon and get the 920?

hi my nastrme is Toni,
Have a HTC thunderbolt and have a 2 yr. contract with verizon with grandfathered in unlimited wireless contract that is up in 2 months. Can The HTC phone be converted to Straight Talk Wireless network? or am I stuck staying with verizon . need a good photo phone and wifi,,, travel all over united states and am in some strange places with roaming!

Your best bet is to:

a) Get a new phone (compatible with T-Mo: Lumia 521/925), and have a T-Mo Straight Talk sim. Why T-mo? Last time I heard is that ATT sims are rare to find, and ST don't carry them anymore.
b) Find a Verizon mvno
c) Find an ATT mvno instead of ST, and get an ATT compatible phone...
 
So an unlocked 920, 8x/s, ativ, would work on straight talk? I've got ~6 months left on my ATT contract and will be switching to a cheaper network. Would be nice to get an unlocked phone now and keep it when I change networks.
I have unlock 920 and drops call on and off everyday !! ATT has 45.00 unlimaited now !!and as soon as my mins is up with straight Talk I am going back to ATT