phone keeps disconnecting during call

Hi there, dottie118!
Thanks for reaching out to the Apple Support Communities! It sounds like you have an issue with calls being disconnected and I am happy to assist! Take a look at this article with steps to follow If you can't make or receive calls on your iPhone. While this article specifically talks about not being able to make or receive calls, the steps are great for issues with calls not staying connected. It also gives you the next steps to take if the issues continue.
Cheers!+