StraightTalkSIM.com to order your compatible sim (AT&T or T-Mobile), then you choose port your number and pay the $14.99 for the sim card and wait for it to arrive. However I would recommend porting it to Google Voice to get the phone number for life. See Google.com/Voice (Currently not compatible with MMS/Video Message/Picture Message.
Buy the Straight Talk phone and airtime card. If you want an Android phone you have to buy a $45 unlimited talk, text and web airtime card.
Go to this page.
Choose the third option.
Activate my Straight Talk phone with a number transferred from another company.
Make sure to have your Verizon account number, pin number and contact information written down so it is easier to port your Verizon service to Straight Talk.
The Samsung Galaxy Proclaim will use Verizon towers for service. If you buy the Proclaim you will have the same service as you do with your current phone.
If you have any more questions message me and I will try to answer them the best I can.