I'm not sure about your annoyance. But, I'm thinking that it's more than just the "my baby" that's bothering you. You're sounding unhappy about phone calls too. That is u to me. I love my son and speaking to him a few times as week seems okay. I called my own mother everyday, sometimes more.
But! If it makes you feel better, my sil s had dc when mil was 40s. She didn't want to be called grandma or any derivative of grand.
She was called Mama84. Well! I'm mama84! So I insisted she be called grandma first name. I'm still considered a rotten dil. She doesn't seem upset now (She was 70 when we had our ds) but her other grandchildren and everyone else is unhappy. Somehow I'm disrespectful. Sils were married. They didn't have the same last name as their mother.
Really?! I really REALLY am Mama 84! It's my last name and my baby. She is granny 84 at best.
But in the end, she loves being called grandma first-hand bc it's associated with love.
I've been a dil for nearly 30 years, my dh is very grateful to me for being patient and kind to her. He knows that she is wicked.
Try to be patient, family should come first and as much as she hurt me, repeatedly, for fun and pettiness. She is a good grandmother and the more people who love my dc, the better.
Take care, congratulations!