Features 3-113 Features CCall BarringCall Barring is a system programmable feature that can prohibit certain extension users frommaking unauthorised toll calls.Every extension is programmed to belong to one of 5 classes of service (COS). Each COS isprogrammed to have a call barring class for day mode, night mode and lunch mode.There are 5 call barring COS numbers available. Call barring COS number 1 is the highestclass and the COS number 5 is the lowest. That is, COS number 1 allows all toll calls. COSnumbers 2 through 5 are used to restrict calls by combining pre-programmed deny andexception codes shown in the table on the next page.Denied CodesAn outgoing outside call made by an extension with a call barring COS number between 2and 5 is first checked against the assigned denied codes in program [302]-[305].If the first digits of the dialled number (not including the line access code) are not found inthe class, the call can be made. Each class can store up to 20 denied codes, each consistingof 11 digits.Exception CodesThese codes are used to override a programmed denied code. A call denied by the deniedcodes is checked against the selected exception codes assigned in program [306]. If a matchis found, the call can be made.Up to 80 exception codes, each consisting of 11 digits, can be stored. The available numberof codes depends on the COS number.• Emergency numbers, such as the police or fire station, should be stored in program[309] “Emergency Dial Number Set” so that they are exempt from call barring.• If a stored Host PBX access code in program [403] “Host PBX Access Codes” or a storedcarrier code in program [300] “Carrier Excepted Code Assignment” is found in thedialled number, the subsequent telephone numbers will be checked for call barring.• The interdigit timer assigned in program [208] “Interdigit Time” applies until the callbarring check is completed. When the timer expires, an outside outgoing call will bedisconnected while dialling, if “Enable” was selected in program [211] “No DialDisconnection”.• The call barring class for a locked extension can be assigned in program [312] “CallBarring – Extension Lock Boundary Class” so that even a locked extension can make alocal call, etc.• It is programmable whether the “ ” or “#” the user dials is to be checked or not on theCall Barring code in program [125] “Call Barring Check for and #”. This is useful toprevent unauthorised calls which could be possible through certain Local Exchangesystems.• Required System Programming[301] Call Barring – System Speed Dialling Boundary Class[302]-[305] Call Barring – Classes 2 through 5 Denied Codes[306] Call Barring – Exception Codes[601]-[603] Call Barring – Class of Service Assignment – Day/Night/Lunch• Related Feature ReferencesEmergency CallCall Barring – Extension Lock Boundary ClassCall Barring for System Speed DiallingCall Barring Override by Account Codes!!+
