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Long-Distance Control Table
This table controls the level of authority of an outgoing call that is dialed through FXO and diverted to
PSTN, as below:
The long-distance control table controls the level of authority of an outgoing call through FXO.
Instruction:
Ÿ
If Level 0 (the highest level) is set to prohibit dialing any number started with prefix 0204, then any
level below 0 (including Levels 1 to 5) is also prohibited.
Ÿ
If Level 1 is set to prohibit dialing any number with prefix 0, then any level below 1 (including
Levels 2 to 5) is also prohibited. Since Level 0 is not restricted to any prefix, therefore at level 0
users can dial a number with the prefix 0.
Principle: Downward Restriction
If the users at a higher level cannot dial a number with a
certain prefix, then users at lowers level also cannot dial a number with the same prefix.
Long Distance Exception Table
This table handles any exceptions to the long-distance call table.
Instruction:
Ÿ
According to the Long Distance Control Table, users at Level 2 are prohibited to dial a number with
the prefix 0. But, if a prefix 09 is set in the Exception Table, then the users at Levels 1 and 2 could
then dial any number with the prefix 09.
Ÿ
According to the Long Distance Control Table, users at Level 0 are prohibited to dial a number with
the prefix 0204. But, if the number 020488988 is set in the Exception Table as above, then users
could then dial this number.
Principle: Upward Opening
If the users at a lower level can dial a number with a certain prefix,
then the users at higher levels can also dial a number with the same prefix.
Summary of Contents for voicecom
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