- High quality Stainless steel - Suitable for all PBX with SLT/FXS ports - Works on 24V or 48V PBX, PSTN line or 12 volt local power - Adjustable ring timer - Adjustable call timer, up to 17 minutes - 2 Inbuilt relays can activate device(s) - Detects busy tone to release the call - Flush mount (pictured) with optional surface mount case available (AN SMB or AN SMBV)