Random Beeps while on Phone/Video call

It might be a call waiting signal.

Hey there, and welcome to Apple Support Communities, Chimera1!

From our understanding, you're hearing random beeps while talking on the phone or making video calls. We can certainly understand your concern and can help provide some insight. First, we would like to ask you a couple of questions in order to get a better understanding. That being said, what exact version of iOS are you currently using? We ask as the menus and options can change slightly between versions of iOS, and we want to make sure we provide the most accurate steps. You can locate this by going to Settings > General > About. Also, is there any other application running in the background when this issue happens? Finally, has the device suffered any physical or liquid damage recently?

We thank you for your answers, they will help guide us to the next troubleshooting step.