When I am talking to someone on my phone, my voice cuts in and out on their end

Hi there, helendoro.

I see that you're having a problem when using your iPhone as a phone. The your caller says your voice starts and stops, and I'm glad to help.

If the microphones on your iPhone, iPad, and iPod touch aren't working -- If this is only happening with one person, it's most likely their phone. If it's happening frequently, make sure your microphone is working as expected.

Take care.

Thanks again, helendoro. Since the issue is still present, I'd like you to contact Apple Support.

Apple - Support - Product Selection — After selecting this link, type "call" in the Search topics field and select "Calling, voicemail, or other phone functions not working as expected" from the Results. Then select how you'd like to start the conversation.

Have a great day!

Thanks for getting back to us with that information, helendoro. It’s helpful. Please perform the steps in the article that was previously shared to you while you’re at home.

Cheers!