Route Selection

The function for route selection is realized by means of analysis tables. After a dialed number is analyzed, the call is handled according to the data specified in the tables.

The following are analysis tables:

• External Number Table (ENT)
• Number Length Table (NLT)
• Destination Number Tables (DNT1 and DNT2)
• Fictitious Destination Table (FDT)

The order in which a number is analyzed in these tables is shown below.

External Number Table

For each number stated in the ENT, the following data may be given:

• Number of leading digits to delete
• Digits to insert at the beginning of number
• Indication of whether the number is a conflict number (conflict numbers are those with the same leading digits but with a different number length; for example, if both 12 and 123 are valid numbers, they are in conflict and a time supervision has to be performed after the second digit in order to see if any more digits will arrive).

If no match is found for a dialed number in the ENT, the number will next be analyzed in the NLT.

Off-net to on-net conversion:

The function off-net-to-on-net conversion is realized by means of the ENT table. By initiating numbers that are to be found in the own exchange or within the private network as entries in the ENT table, LCR can convert these numbers to any complete or incomplete internal or external number.

Number Length Table

For each number stated in the NLT, the following data may be given:

• Number of leading digits to delete
• Digits to insert at the beginning of number
• Indication of whether the number is a conflict number
• Maximum number length
• Minimum number length
• Indicator telling if the area code is to be inserted between the LAC and the rest of the analyzed number

If no match is found for the dialed or rearranged number in the NLT, the number will next be analyzed in the DNT.

Destination Number Table

The Destination Number Table is divided into two tables, the Exceptions Table (DNT1) and the Number Table (DNT2).

DNT1 holds those numbers which are exceptions to the more general analysis cases that exist in the Number Table. This means that a number which is to be analyzed is first matched to the numbers in DNT1, and, if found there, the Destination Number analysis is completed. If the number is not found in DNT1, DNT2 is tried.

For each number stated in DNT1 and DNT2, the following data may be given:

• Number of leading digits to delete
• Digits to insert at the beginning of number
• Information whether an account code is required
• Index to the FDT where the selected destination code is stored
• Indicator telling which Toll Restriction Class of Services are allowed to complete the call
• Information telling what type of external number the dialed (or rearranged) number is
• Information telling which Transit Network Selection to use for this destination
• Information telling which local or network operator to access for this destination (Operator System Access).

When the LCR analysis is completed, the resulting number is analyzed in the external analysis in order to find a Route Choice Table (RCT). This RCT contains one first-hand route choice and up to seven alternative route choices.

For each route choice, the following data is stored:

• Route number
• Indicator telling if this route choice is marked for threshold 1 or threshold 2 or none (LCR Class of Service).
• Indicator telling if this route choice is marked for sending of Expensive Route Warning Tone (Expensive Route Warning Tone).

Capacity

The maximum number of entries for the different tables are as follows: