Using existing wireless contact sensors

Hello, I recently moved to a new place and the previous owners have installed contact sensors on all the entrances. They were using Xfinity's security service for sometime but then they disconnected it. I have all the sensors installed so it really doesn't make sense to pay for the sensors again. I was wondering if its possible to maybe buy Ring's Base station and use Ring for security since we already have the Ring doorbell 2 installed. Thank you