All of these sites require the use of a credit or debit card for payment and also as a proof of age.
Adult Verification Sites
Important note to parents / guardians.
Lineisp tries to ensure safer surfing for younger people while recognizing that some adults may prefer to view material which other would feel uncomfortable with. If you have younger children who may use the Internet, you are encouraged to download and install one of the child protection filters (some of them are completely free). It will not stop adults using the system as they see fit (providing they remember the password they choose when installing the filter).
To visit the page which allows you to download the filters, please click here.