You could use a real radio personality (like in the Delilah project below), or you could make up your own radio personality from the fictional world that you are writing about: the Brothers Grimm, Ganesha — any kind of character could host a call-in talk radio show.
If you are using a real radio personality, look at Wikipedia to learn some details about their show; all the major radio talk shows and personalities have Wikipedia articles: Delilah, Dr. Laura, Car Talk, etc.
For an example, here is a Rama-and-Sita Storybook based on the Delilah radio show: Delilah's Radio Hour. It's by Kate Carlton Greer, who you may know from KGOU radio! She graduated from OU a few years ago and now has a real career in radio: Kate Carlton Greer.