Details vary significantly from one platform to another, but the provider may be given a personal page on the platform to use however she (sometimes he) wishes.
Once means of transmitting payment were developed, phone sex turned into primarily a commercial activity, with customers (overwhelmingly male) and sellers (overwhelmingly female).
When the Internet got relatively mature, sale of any sexual service not involving a minor could be made to anyone not a minor.
Software platforms were custom written to handle money collection and transfer, connecting caller and sex worker though neither could see anything but the platform's phone number, and metering the connection.
Due to the potential for emotional intimacy between those who have engaged in phone sex, it is a matter of some debate whether phone sex is to be considered infidelity when involving a person outside of a committed personal relationship.
Nevertheless, phone sex should not be confused with prostitution wherein money is exchanged for real life sexual services or physical interaction.
Big platforms as of 2016 are Niteflirt, Talkto Me, and My Phone Site; the latter also includes provision by which a manager, with the consent of the providers, could have a virtual shop with many providers under them. Customers had a variety of payment options, and pages of providers to choose from, sometimes with voice samples available.