ipad and iphone live voicemail

I received a call this morning, where a voicemail was left on my phone. When I have gone to my iPad, the voice mail is showing in the phone app, even though this is all turned off on the ipad and the iphone.

I don't want my phone on my iPad, as i want to be able to keep them separated.

There is always a chance that I have missed a setting, but this was not happening before. I am struggling to see what i have missed. The "receive on other devices" is switched off on my phone and the ipad has a different number on the sim.

Thank you in advnace.