Unlinking iPhone from iPad but still being able to use iPad for calling

Currently my iPad and iPhone are connected, meaning when someone is calling me it shows up on my iPhone and iPad. How do I unlink this feature? I want to still be able to use my iPad for calling and receiving calls on its own. Ideally that would mean I could use my phone to call one number and then using my iPad for calling a different number. Also I'm currently on hold for over 45 minutes. I transferred the call to my iPad, but I need to use my phone. ( I am an agent who does a lot of phone prospecting) I don't want my call to on my iPad to be ending if I hit the end button on my iPhone. How do I unlink the two without loosing my current call? PLEASE HELP!