SMS socket, SMS plug-in, remote control module, remote control and switching. Extension for SMS Butler M1 V4, the slave can communicate with the master via a radio module. Control electrical devices via SMS or phone call. LED indicators for relay status and signal condition. Calendar function with daily and weekly schedules, delayed switching. Permissions: The SMS Butler can be set up with one master user and four family member users. All have the permission to send switching commands and check the status. Additionally, the master can make configuration adjustments. Notification for weak GSM signal: The socket sends an SMS notification when the GSM signal is too weak. This function must be activated by the master first. Control via password-protected SMS: By default, only the master and the four family members have the permission to turn the device on and off. For other unregistered users, the password switch function can be used.