iphone 7plus Video Call Not working.

Did you update to ios 14.5 . You can also reset your phone to factory default and then set it up as a new phone and not from a back up.

also try this: You might need to sign into your Apple ID account when you turn it on again. On an iPhone or iPad, go to Settings > FaceTime. Use the toggle at the top of the page to turn FaceTimeoff, then tap it again to turn it back on. 

See if this works, if not get it check from a apple service centre.

Go to Settings > FaceTime and make sure that FaceTime is on. If you see "Waiting for Activation," turn FaceTime off and then on again. ... If you don't see the FaceTime setting, make sure that Camera and FaceTime aren't off in Settings > Screen Time > Content & Privacy Restrictions > Allowed Apps.

If you can't make a FaceTime call on your iPhone, iPad, or ...