By definition, practically everyone who has access to the web has access to a phone or cell – which is why if you are not offering phone billing you are missing out on a whole new source of income.
Whilst such billing is the solution to making money from the majority of the world's population who do not have a credit card, there are a whole army of people in the developed world that have one, but would prefer not to use them online.
Since the telephone is still an essential utility that acts as a lifeline to the outside world, people tend to pay their phone bills on time, which is why phone billing works. The Telco's worldwide are effectively acting as payment collection agents on your behalf.
In those countries that support them, the surfer calls a local premium (1-900) number which is charged at a premium rate. In those that don't, the surfer makes a regular International Direct Dial (IDD) call to a country with which the processor has a revenue-sharing agreement in place with the telecommunications carrier of said country.
When his phone bill arrives on the surfer's doormat at the end of the month, his 'online' purchase is effectively hidden amongst the dozen's of other less contentious uses, such as calling up Grandma to wish her a happy birthday.
Furthermore, the URL of the underlying website visited will never be quoted – so no awkward questions from a prying wife! This is another small but crucial reason that phone billing is popular with surfers; it's quick, convenient and above all anonymous – great for the spontaneous purchase.
When choosing a processor with whom to partner for such billing, it is important to choose one which works with surfers who only have one phone line. Several solutions exist out there that grant surfers access to your member's area whilst they are simultaneously connected to a premium number – but given the fact that the surfer needs another line for connection to the Internet, such solutions are wholly inadequate for the majority of the world's surfers that do not have the luxury of two phone lines.
Since people tend to pay their phone bills in full, chargebacks are very rare; ironically, as with mobile adult services, the one notable exception to this rule is the U.S., where consumers are not obliged to pay the 1-900 element of their phone bill.
But the world is a big place and given the global nature of the Internet, the sooner you start offering phone billing as an additional option on your join page, the better for the surfer, for you, and for your bank manager.