I remember when phone sex lines took off circa 1981 (I was vacationing in Florida where the fad hit before the rest of the world caught on), exploited early on by Gloria Leonard. This much older porn film anticipates the concept, only misses the boat by failing to recognize the commercial potential.
I don't want to accuse the Something Weird staff of sloppiness, but on Vol. 69 of their Dragon Art Theater series they had the temerity to title the film Melissa's Hot Line. The character is clearly called Melanie in the film -all they had to do was watch.
She's watching TV with her boy friend, who suggests they have a diversion by making some obscene phone calls. The girl (my fave, Joan Devlon, looking great) who picks up on the other end of the 3rd call takes over, treating our couple to the sounds of some heavy duty sex (which we're shown in extreme closeup).
They arrange to all get together (oops -sounds like a forerunner of the current dangers of chat room-inspired meet-ups with predators!), with a big black dude named The Whip coming along; he's played by forgotten but briefly busy porn performer Pharoah Amos.
Before the anticipated 6-person orgy we get to see The Whip mete out some punishment in his Satan's dungeon. The orgy even features whipped cream, another big deal back when.
Making this eminently watchable is the turn-on beauty of both leading ladies, Devlon classy no matter what XXX action she's involved in, and Justina Lynn -cute with a great bod in the title role.