Adult chat lines (phone sex) and tech support are a very common use of premium-rate numbers.
Other services include directory enquiries, weather forecasts, competitions and voting (especially relating to television shows).
These telephone numbers are usually allocated from a national telephone numbering plan in such a way that they are easily distinguished from other numbers.
Another now-uncommon premium-rate scam involves television programming that induces young children to dial the number, banking on the notion that they will be unaware of the charges that will be incurred.
One variant, targeted at children too young to dial a number, enticed children to hold the phone up to the television set while the DTMF tones of the number were played.
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.
A 1-900 telephone number, in the North American Numbering Plan, has the form 1-900-###-####, and is often called a 900 number or a 1-900 number ("one-nine-hundred").