It turned out to be/It turned out it was

[Topstudent]

I wrote this:

I was worried for her, so I called the number she had called from my phone. It turned out to be/it was her mom, who told me that...

What would be correct and natural here?

 

[Skrej]

First, it's unclear what number you're calling. It sounds like she previously called a number using your phone, and now you're calling that same number (i.e. a number in your phone's dialed history). While that's possible, I'm not sure that's what you want to say.

Do you mean you're returning a call from a missed number, and that number ended up being her mother? Is it her mother's number, or is her mother answering her daughter's phone?

Regardless, either of your options would work. I suggest you clarify how you got the number you're dialing, however.

 

[Topstudent]

First, it's unclear what number you're calling. It sounds like she previously called a number using your phone, and now you're calling that same number (i.e. a number in your phone's dialed history). While that's possible, I'm not sure that's what you want to say.

That is what I want to say. She previously called a number using 'my' phone, which turned out to be her mother's number.

 

[tedmc]

I think "turn out to be" gives the impression of of unexpectedness and discovery, which the second version doesn't.