How do I implement call accept and reject feature via BLE?

[vishesh-varma]

Is there a standard service that handles acceptation and rejections of calls natively? I know that I can do this with an application for my BLE device, but I see headphones do it without needing an application, so I'm presuming that it is possible, somehow.
I also see smartwatches with this same feature, but they almost always have a companion application.

Also, is the same service also available to work with iOS devices?