This standard specifies the general requirements for the performance, reliability and security characteristics of alarm transmission systems. It covers the general requirements for connections providing signaling between an alarm system and an alarm receiving centre. EN 50136 shall apply for transmission of all types of alarms; fire, intrusion, access control social alarm etc. Different types of alarm systems may in addition to alarm messages also send other types of messages, e g fault messages and status messages. Also these messages are considered part of alarm transmission. The term alarm is throughout the document used in this broad sense. Additional requirements for specific types of alarm transmission systems are given in separate parts of this standard. This does not preclude the use of any alarm transmission system not covered by one of these specific parts, provided that it meets these general requirements. It further does not preclude the use of the alarm transmission equipment outside the scope of this document