Here is an oddity for you.
My DIL is currently working in Sosa. (Somewhere in Germany).
This morning the house phone rang, and I answered it to find it was her on the other end.
It is a phone she only uses for work.
Hello, she says, how did you get this number, and why are you ringing me?
I told her, I don't know your number, my house phone rang.
She explained she was in a conference call with colleagues, and had had a message to say there was a call waiting.
To say I don't get it, is an understatement.
Any clues?
Sorry I don't know the answer but I had a similar experience a few years ago. I picked up my phone and dialled a number and one of my friends answered, but I didn't ring her number! Must be crossed wires or something!
I know nothing about Smart Phones but I am going to have a guess.
Your DIL has your telephone number recorded in her mobile and , somehow, it automatically dialled your house phone; possibly at the very moment she was about to telephone someone else.
In attempting to respond to the call waiting she selected the wrong option by mistake and called your number which is obviously stored in her phone's memory.