Because you have a basic/messaging phone now, and would need a smartphone data plan, you may have to be on the new Verizon plan. In the past Verizon has not allowed plan changes on older, grandfathered plans. The computer system can't add a data plan for a plan that no longer exists. This automatically means you cannot use a 2 year contract because you have to use a currently offered plan and the current plan (Verizon plan) does not permit contract purchases.
Rumor is Verizon will be ending the contract option soon, so you may have to look at the Device Payment plan anyway.
I suggest you ask in the Verizon forum if you can add a data plan to your line on the existing family plan, or if you have to switch to the current plan.
You will need to create a community user name and password.
https://community.verizonwireless.com/content
So I currently use a LG Cosmos 3 which I have had since May 30, 2015. My carrier is Verizon and my current plan is 500 MB data, and unlimited talk and text, shared with my mom, sister and dad, my dad is the only one with a smartphone. I want to buy a Samsung Galaxy S7 Edge around the May/June this year. Wherever I look to buy it it mentions a 2 year contract which is $229. Does this mean that phone plan payments are paid for for those 2 years? Will I be able to add the phone to my current plan? Additional Costs? And will I be able to keep my phone number? Thanks for your help.

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