when I FaceTime i can see and hear the recipient but they say that my voice and picture keep going on and off

Hi

Welcome to the Apple Community!

Re: they say my voice and picture keep going on and off

Seems likely that the wi-fi or cellular connection you are using may not be strong enough.

Apple support has an article online with some "trouble-shooting" tips with in it:

If you can't make a FaceTime call on your iPhone, iPad, or iPod touch - Apple Support

Eg: Make sure that both you and the person that you're calling are using a fast Wi-Fi or cellular connection.

If you’re using Wi-Fi, FaceTime requires a broadband connection.

Update your device to the latest version of iOS.

If your cellular connection or Wi-Fi network are running slow,

or other users are streaming audio or video on the same Wi-Fi network,

you might have these issues:

• • • Connection alerts or unable to connect
    • Choppy video calls
    • Black screen
    • Dropped calls

Hope this helps :-)