Screening Examples

Several configuration examples are offered here to show how the RCOS works. If you were to configure an RCOS as shown in the table, the system would process dial strings as shown in the following examples.

Example Configuration
Parameter Value
Home NPA 408
Starting digit position of NPA 10
Ending digit position of NPA 8
Starting digit position of NXX 7
Ending NXX digit position of NXX 5
Digits to be absorbed 9,1,91
Exact match table is set to disallow 5551212,411
NPA table is set to allow 408,415,510
NXX table for the NPA 408 is set to disallow 662,684,728

If a dial string is 914084283558, the system:

  1. Removes the 91 in accordance with the absorption table.

  2. Compares to the exact match table and finds no match.

  3. Compares the NPA 408. Because the NPA 408 has an associated NXX table, it is used.

  4. Places the call because the NXX table is a disallow table and does not contain the prefix 428.

If a dial string is 2551234, the system:

  1. Compares to the exact match table.

  2. Adds the home NPA.

  3. Compares the NPA 408. Because the NPA 408 has an associated NXX table, it is used.

  4. Places the call because the NXX table is a disallow table and does not contain the prefix 255.

If a dial string is 14154244567, the system:

  1. Removes the 1 in accordance with the absorption table.

  2. Compares to the exact match table.

  3. Compares the NPA 415. Because the NPA 415 has an associated NXX table, it is used.

  4. Blocks the call because the NXX table is a disallow table and contains the prefix 424.

If a dial string is 95551212, the system:

  1. Removes the 9 in accordance with the absorption table.

  2. Compares to the exact match table and blocks the call because the number matches and the table is a disallow table.

If a dial string is 15102265678, the system:

  1. Removes the 1 in accordance with the absorption table.

  2. Compares to the exact match table.

  3. Compares the NPA 510. Places the call because the NPA 510 does not have an associated NXX table and the NPA table is set to allow.

As the preceding examples show, NPA/NXX call screening works well for domestic outdials. For restricting international outdials, the best method is to limit the number of digits that can be dialed to less than the length of an international telephone number. Do this with an LCOS that includes any of these limits parameters, as appropriate:

  • NP WakeUp – Phone Length

  • Maximum Number of Digits for Telephone Number

  • Message Delivery – Phone Length

  • Message Phone Length

  • Paging – Phone Length

Then assign this LCOS to the desired mailboxes. Refer to the Limits Class of Service section for information about LCOS configuration.

Parent topic: Restriction Class of Service
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