Is it permissible to open an "Internet Cafe and Communications" business despite the doubt regarding the impermissibility of using the internet for unlawful matters, or the customers' failure to perform prayers, or the nature of the phone calls they make, and is the business owner responsible for that?

It is advisable to seek another lawful job, because an internet cafe is often not free of Sharia (definition)-prohibited elements, and its owner incurs sin for causing its patrons to fall into sin. Furthermore, illicit money enters his wealth in exchange for forbidden use. If he is determined to open it, he must adhere to the Sharia guidelines mentioned in Fatwa (definition) no. 32772.