Telephone companies typically offer blocking services to allow telephone customers to prevent access to these number ranges from their telephones.In some jurisdictions, telephone companies are required by law to offer such blocking.
At that time, the intent for area code 900 was as a choke exchange—a code that blocked large numbers of simultaneous callers from jamming up the long distance network.
This practice continues, along with the use of these numbers for things such as software technical support, banking access, and stock tips.
Adult entertainment 900 numbers have been largely absent from AT&T and MCI since 1991.
Other early leaders in amassing huge volumes of revenue were the New Kids on the Block and Dionne Warwick's Psychic Friends Network.
Consumers in the US have specific rights regarding 900 number calls, as laid down by the Federal Trade Commission, such as the right to a disclaimer at the beginning of the call and a subsequent 3-second hang-up grace period, the ability to contest billing errors, a prohibition on marketing to children, and a requirement that telecommunication companies must allow the consumer to block dialing to 900 numbers.