Prostitution may be brothel-based or non-brothel based as in the case of call girls.Prostitution is illegal in India, causing prostitutes to work underground.The total number of prostitutes in Kolkata is unknown.
Finding sex workers or escorts in Kolkata is very different than many other parts of the world.
There are these guys called "service provider"s (SP), and you can try to contact them first and ask what kind of girls do they can offer.
Streetwalkers in Kolkata are the lowest level of the prostitutes.
They are unbelievably cheap, but you pay what you get as most of them are not attractive and or healthy.
Even in Durgapur which is nearby Asansol and 170 KM away from Kolkata there is also a small red light area named Kadaroad near to main gate DSP.