In concept they have a lot in common with platforms such as Ebay: the seller provides the picture(s), description, and sets the price, a percentage of which is kept by the platform.In the sex industry, similar platforms emerged facilitating the selling of used panties and other odoriferous garments, and for "cam" video sessions, in which the customer, for a fee, can direct the woman on the video screen, and for a higher fee, have a private connection (no one can see caller or provider except each other).
By the end of the 1980s, nearly all of the major local phone companies in the United States, plus the major long distance carriers, were actively involved in the adult chat line business.
The telephone companies would provide billing services for chat line companies.
The incentives for providers were then reversed; rather than earning money from keeping the customer on the line (orgasm delayed), they earned more from bringing the caller to orgasm quickly, so as to move on rapidly to another call.
Unused minutes were rarely usable on a second call.
Originally phone sex services consisted of a managed network of dispatchers (live or automated) and erotic performers.
Performers would come to a studio where they received a cubicle, coaching, and cash incentives to keep callers on the line longer.
The provider provided (say) 10 minutes of service, but got to keep all of the money (say 20 minutes).
When the Internet got relatively mature, sale of any sexual service not involving a minor could be made to anyone not a minor.
Phone sex takes imagination on both parties' part; virtual sex is difficult if the operator does not put the images in the head of the caller and the caller must be open to the pleasure as well.