Call from ME User to PBX Extension

The ME user dials an internal extension number, and the MEINS or NMES adds the required R1/R3 number in front of the dialed B-number. These numbers, along with the Mobile Subscriber ISDN (MSISDN) A-number, are sent on the DID ISDN trunk to the PBX. The ME application detects that the received A-number belongs to the ME number plan and translates the MSISDN number to the internal PBX number. This number is forwarded to the receiving terminal if A-number presentation is enabled.

If the ME user dials the national (with city code) or international number (with “+”, country code, and city code), to the PBX extension, NMES must detect the number as an internal number in that PBX and just add R1/R3 in front of the number.

Figure 1. Internal Call from an ME User to a PBX Extension

Figure 2. Internal call from an ME user to a PBX extension

This call scenario can also bee seen in table form: