I have a 5501 Verizon jetpack with the old, true unlimited plan. I want to keep the plan and to do that I can't make any changes, none, nada, zilch or I will lose it. I want to upgrade my jetpack but if I buy a new one from Verizon that is a change and I lose my unlimited plan. I've been told I can buy a jetpack from a 3rd party vendor, E-bay for instance, replace that device's sim card with my current sim card and keep my unlimited plan. Has is anyone done this and is so, does it work? I'm not real tech savvy so am hesitant to make the purchase.