I came out as trans to my grandma, over the phone. Here's a rough transcript of what happened:
Me: Hi grandma!
Grandma: Oh, hello dear. Who is this?
M: it's me, [legal name].
G: Oh, hello. How are you doing?
M: Not too bad, not too bad.
G: Well, that's good. Are you looking for your mother? I think she's...
M: No Grandma, [Mom's name] is on her way back to Minnesota. I want to talk to you, and I've got something important to say.
G: Well all right, spit it out.
M: I'm... My name isn't [Name] anymore. It's William.
G: Oh, all right, but isn't William a boy's name?
M: Yes it is, and that's the other part of what I want to say. I'm a boy, grandma. I just wound up with a girl's body.
G: Well, how do you know that?
M: It's not something that's easy to explain, grandma, but I feel it in my heart. It's a lot more comfortable for me when people call me William, and when they say "he" instead of "she" when they talk about me.
*awkward pause*
G: Did it hurt?
M: Did what hurt?
G: Becoming a boy.
M: *laughs* No, it didn't hurt.
G: Well, all right. *unintelligible background voices - my grandpa and the in-home caregiver* Yes, just a moment.
M: What's going on?
G: It's time for me to take my medicine, but I'll be praying for you, William.
M: Thanks, Grandma. Talk to you later.
G: God bless you, dear. Goodbye.
M: Goodbye.