This European Standard specifies the general equipment requirements for the performance, reliability, resilience, security and safety characteristics of supervised premises transceiver (SPT) installed in supervised premises and used in alarm transmission systems (ATS). A supervised premises transceiver can be a stand-alone device or an integrated part of an alarm system. These requirements also apply to SPT’s sharing means of interconnection, control, communication and power supplies with other applications. The alarm transmission system requirements and classifications are defined within EN 50136-1. Different types of alarm systems may in addition to alarm messages also send other types of messages, e.g. fault messages and status messages. The term alarm is used in this broad sense throughout the document. Additional requirements for the connection of specific types of alarm systems are given in the relevant European Standards. Because the SPT can be applied in different applications (e.g. I&HAS, fire and social alarm systems), requirements for the SPT, additional to those of this European Standard, may be specified in separate application specific documents. This European Standard specifies the requirements specific to alarm transmission. Application specific requirements for the connection of the SPT to specific types of alarm systems are given in the EN 50131 (all parts) for I&HAS, and EN 54 (all parts) for fire. For other SPT applications, see the relevant National or European standards.