Dial codes

Before a call can be rated, DUAL Softswitch needs to establish the country, and optionally the city, for which the call is destined. This is defined using Dial Codes. Dial Codes provide a match between the dialled numbers and a textual description of the destination. They also define the length and format of valid numbers. Examples of Dial Codes are shown in the table below:

Digits	Destination	City	Country length	Minimum	Maximum
44	UK		2	9	10
4420	UK	London	2	10	10
447	UK - Mobile		2	10	10
447973	UK - Mobile	Orange	2	10	10

Each row represents a separate Dial Code definition. The means of each column are:

Digits

This is the digit string against which the E.164 format of the dialled number is compared. The longest possible digit string is used for the match. For example:

•	441293888500 would match the 44 Dial Code entry.

•	442071060706 would match the 4420 Dial Code entry.

•	447700654321 would match the 447 Dial Code entry.

•	447973654321 would match the 447973 Dial Code entry.

Destination / City

These fields define the textual descriptions for each Dial Code entry. These have two purposes:

1.	They are used to seek a match against a tariff table for establishing the per minute cost of a call.

2.	They are used to show the destinations in the CDRs displayed on the various control panels.

Country Length

This can optionally be used to improve the display of dialled numbers on the CDRs at the DUAL Softswitch control panels.

This field specifies the length of the country code and allows the CDRs to be formatted accordingly. For the UK, the Country Length can be set to 2 and would result in the formats shown in the table below. If Country Length is not set, then dialled numbers will be displayed as single strings with no "+" symbol and no space.

E.164 format	Dialled number in CDR	Description in CDR
441293888500	+44 1293888500	UK
442071060706	+44 2071060706	UK (London)
447700654321	+44 7700654321	UK - Mobile
447973654321	+44 7976654321	UK - Mobile (Orange)

Minimum / Maximum

These two optional fields define the minimum and maximum permissible number lengths for each Dial Code entry. These lengths do not include the country code, the length of which is determined using the Country Length definition. If a call does not confirm to these number lengths, then it is rejected using ISDN cause code 28.

You can reach the Dial codes page by clicking on the Dial codes link on the left sidebar within the Routing box. From this page, the current dial codes can be downloaded in Microsoft Excel format, and these can be used as a template for preparing future dial codes.