What are call prefixes


A call prefix is an important property of the call service. The call prefix defines the number rule of the call connection, and reflects the numbering and routing solution of a switch office. The call prefix determines the service type of a dial rule (a basic service or a supplementary service; an office internal service, a local call, or a toll call), and specifies the length of numbers. The call prefix can also be used to control call rights.

A private branch exchange (PBX) system verifies the validity of the numbers dialed by users based on call prefixes, and processes the numbers. Proper call prefixes are critical to a successful service configuration. Users' calls must match call prefixes so that calls can be connected. One or more call prefixes may be matched during a call (a basic service or a supplementary service).

Other related questions:
What is the call prefix of the AR router
A call prefix, an important attribute of the call service, defines a call number rule and describes the call number distribution and routing plans in an exchange office. A call prefix identifies the service attribute (basic service or supplementary service; intra-office call, national long-distance call, or international long-distance call) of a dialing plan and determines the range of dialed number length. Call prefixes can also be used to control call permissions. A PBX checks the validity of a dialed number and connects or rejects the call based on the call prefix. A call can be connected correctly only if the call matches the correct call prefix. Therefore, a correct call prefix configuration is the key to the call service. A call must match at least one call prefix.

How to add prefix for called number on U19
It can be done by Configuring number conversion for associated prefix. Please refer to the product document: ; Configuration > Configuration Guide > Advanced Configuration > Setting Number Conversion Mode

What configurations are required so that the U1911 deletes the prefixes of the called numbers when terminating incoming calls?
Add the number change rule and set the length of the number to be deleted. When configuring the incoming prefix, reference the number change rule to delete the prefix.

What does the intra-office or local attribute of a prefix configured on the U1900 mean?
When the prefix of the called number matches the prefix attribute configured on the U1900, the system searches for the intra-office called number first. If the called number cannot be found, the system routes the call based on the office route selection code. Application scenario: When the first several digits of an intra-office number overlap with those of an external number, a prefix conflict occurs. In this scenario, a local intra-office prefix is used. After a local intra-office prefix is configured, the system searches for intra-office numbers first. If no intra-office number matches the prefix, the system calls the external user.

How does the U1900 automatically delete the prefix 0 of called numbers from the outgoing call CDRs?
Run the config billpredeal switch on command to enable called number change for U1900 CDRs.

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