These telephone numbers are usually allocated from a national telephone numbering plan in such a way that they are easily distinguished from other numbers.Telephone companies typically offer blocking services to allow telephone customers to prevent access to these number ranges from their telephones.
This type of scam was especially popular in the late '80s to early '90s in the United States before tougher regulations on the 900 number business forced many of these businesses to close.
These numbers were dialed as any other number, such as 976-1234.
A call to either one of these numbers can result in a high per-minute or per-call charge.
Unlike a normal call, part of the call charge is paid to the service provider, thus enabling businesses to be funded via the calls.
While the billing is different, calls are usually routed the same way they are for a toll-free telephone number, being anywhere despite the area code used.