In which legal way can client contact a prostitute?

There are many websites on the internet offering escort services. What is the legal way for a client to contact a prostitute? 1.) To what extent their services are legal if they mention that their services include only companionship and friendship & if the client has sexual intercourse with the woman providing the service, then that is purely personal due to mutual consent and not a part of the services of the agency, will the client still be guilty of availing services of prostitution?     2.) Though prostitution in India is not completely illegal, a number of related activities like pimping, owning and managing a brothel, soliciting in public etc. are illegal. In that case, prostitution is as good as being almost completely illegal because there is no method left for the client to contact the prostitute and vice-versa. If there is, then pls tell me that in which legal way can prostitution exist.