If you think you can write a really great story (and I'm sure you can) why not try writing a script for phone sex. Something that can be used over the phone to make partners hot 'n horny!!
Wouldn't having a script be a little counter productive, Phone Sex should be more like real sex, it should be spontaneous, not set in stone as to what should go on, you should do what feels right and let it go wherever it goes. With a script if one of the people goes off the script what happens? do you stop the scene and start over? It seems like that would just complicate things