If the jet pack didn't come with one or the SIM card in the jet pack might be bad, then yes, you need one.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Let's work together and ensure you have access to the new jetpack. You do need a SIM card so that the jetpack can connect to the Verizon Network. Where did you purchase the device? Usually new jetpack device come with a SIM card already.