Central-stations use special telephone lines, computers and trained staff to monitor their customer's security systems and call the appropriate authorities in the event an alarm signal is received. Typically, there is a fee for services rendered. Because quality and experience can vary greatly among alarm companies, a prospective customer is well advised do their own research before making a final choice. Not all alarm companies monitor the systems they install and may outsource these services to another company.
Some facilities are certified by independent agencies. Underwriters Laboratories (UL) is a leader in inspection and certification of central-stations. UL Standards 827 and 1981 must be adhered to in order to maintain a UL issued Central-Station license. UL conducts annual audits of these licensed facilities to ensure compliance.
"Licensed" companies typically offer higher levels of service and reliability because they are mandated to follow certain regulations.