Verizon will not unlock the iPhone 4S unless it is CURRENTLY active on a Verizon account. Unless you had it unlocked before you moved and/or cancelled your Verizon account, Verizon will not unlock it for you.
Activate it on a Verizon plan. If the plan has been active for 90 days, Verizon will unlock it for you. If the plan hasn't been active for 90 days, you will have to wait until it has been active for 90 days.