3.12 Globalization of Localized Call Ingress on Gateways

This topic describes globalization of localized call ingress.

The figure shows how localized call ingress on gateways is globalized. In the example, the requirements are as follows:

  • Change the calling number from PSTN format to +E.164 format.
  • Change the called number from PSTN format to the format that is used for internal directory numbers.
  • Change the called number from PSTN format to +E.164 format for calls to external destinations (if applicable)

As shown in the figure, the globalization of the calling number can be best achieved by the incoming calling-party settings. An example for a gateway in San Jose is given. Assuming that the calling-party number is provided in the shortest possible format (subscriber, national, international) and with the corresponding type of number information, the relevant calling-party transformation patterns are changed as follows:

  • 5551234, sub -> +14085551234 (prefix +1408)
  • 303555333, ntl -> +1303555333 (prefix +1)
  • 496912345, intl -> +496912345 (prefix +)

The normalization of the called number can be achieved by translation patterns, incoming called-party settings, or significant digits. In the example, the gateway is configured with four significant digits. This approach is the simplest solution but is applicable only if no calls to other external destinations are permitted and a fixed-length number plan with a corresponding DID range is used.

Normalization of Localized Call Ingress from Phones

The figure illustrates how localized call ingress on phones is normalized.

The requirements are as follows:

  • For calls to external destinations: Change the calling number from an internal directory number to the +E.164 format, if not natively used. Change the called number to the +E.164 format if any other format was used (according to the local dial rules).
  • For calls to internal destinations: No normalization is required unless the destination directory number and none of its aliases (enterprise alternate number, +E.164 alternate number) match the number as dialed at the source. An example would be that users must dial access and site codes, but the directory numbers do not include access and site codes and they do not have aliases configured.

As shown in the example, the normalization of the called-party number can be achieved by translation patterns. The normalization of the calling-party number for calls to external destinations can be achieved by configuring an external phone number mask (in the +E.164 format) at the phone and applying the external phone number mask to the relevant translation patterns that are used to normalize the called-party number. Another way of normalizing the calling number is to use the calling-party transformation CSS for calls from this phone. Because this transformation CSS is applicable to all calls, it is only useful if the +E.164 format is also used for internal calls. In the figure, examples for phones that are located in Hamburg (Germany) and San Jose (United States) are given.