So... My answer isn't up there, and I wouldn't expect it to be, because my experience with phone sex is weird. Or, at least, not what most people talk about when they discuss their experience.
I'd done it a couple times before I met M, but by "done it", I mean I sat on the phone with two guys (at different times) while they talked dirty to me and masturbated. I didn't really participate. And because I had no idea what I did was masturbation (long, LONG story), I didn't masturbate while it happened, either.
I've never had phone sex with M, which makes what I'm about to say even weirder.
A few years ago, M had me set up a Skype profile, and have voice chat sex with something crazy like 24 guys in 24 hours. I had to get off with each one, and then block them afterward. At the time, He wasn't interested in repeat customers.
The first few, I did pretty much the same thing. Just kinda sat there, making noises when appropriate, and occasionally saying I liked what they were saying. Until M told me to quit being a dead lay.
I'm not so good with dirty talk. I get tongue-tied on the best of days, and I guess that's what holds me back. I'm afraid I'll stutter over my words, or say something stupid. But that day, I didn't do so bad. And it was hot. And since then, I've been making more of an effort to be vocal. Cause M's one of those weird guys who like it.
So, I guess while it's still a little embarrassing for me, I don't mind it so much. And it can definitely be practice for dirty talk when your face to face with your partner.