Phone sex...Have you ever....?

Anyone who reads this have you ever had phone sex? I am a really shy person, and when I get comfortable with someone I may come peek out of my shell a bit, but never come completely out. So for those of you who has had phone sex; What is the experience like? How can I get myself comfortable enough to open up to things such as phone sex. How do you spark up a phone sex conversation and be serious without being silly. Do you think from your experience that it has sparked up your relationship, or past relationship? What are your thoughts on this? You're advice will be greatly appreciated.