They're both correct but they have different specific meanings. "In my house" is sitting inside the house. "At my house" is less specific. I could mean I am standing in my front yard but would still be considered at home.

they are both correct, Hi, where are you? I'm at my house/I'm in my house

for my the correct is " I'm in my house"

I'm in my house, or I'm at home. They have the same meaning. It's correct to say "I'm at my house" if you want to emphasize this. Say, for instance, someone says "Are you at John's house?" and you respond "no, I'm at *my* house."

Thank you.