My phone made a calling noise but there was no call?

So I was on my phone and suddenly I hear the calling ringtone and I feel my phone buzzing as if I got a call.
But there was no call.
And I could do what I wanted on my phone but it was still making the noise.
I have an iPhone 6s
Why did it do this?

It's haunted, like with ghosts. Your dead relatives are trying to contact you.

Someone dialled your number
and realized they made a mistake.

It's not worth further consideration.