Phone sex was fun when I was traveling a lot for work. It made calls with my wife much more interesting.
An old fuck friend I had would talk on the phone while I had sex with her (not all the time). She said it was fun. She would talk to several of her girlfriends. Only one time did one of her friends asked to join us because it sounded like she was having fun.
Oh I love phone sex and have some very happy memories of an ex-boyfriend who was particularly skilled at it. I spent many a night naked in my bed, bringing myself to orgasm as he described either what he'd like to ge doing to me right now, or what was in store for me next time we met. He turned me on so much one night that I slipped into my long coat and high heels, before driving across town to spend the night with him. Oh such lovely memories!