In this example, the external MSNs and the internal telephones will be assigned "crossed over":
- In the ISDN mapping table, the external MSN '555 555 1' is assigned to the internal telephone number '11', for example. An external call to '555 555 1' will be switched by the LANCOM as a call to '11'.
- By assigning the MSN '555 555 1' to the internal telephone number of the ISDN user '11', the call will be directed over the internal ISDN bus of the LANCOM with the target telephone number '555 555 1'.
Because the ISDN telephone "listens" out for its own MSN, exactly as it used to before implementing the LANCOM VoIP Router, the call is placed to the correct telephone.
Should the LANCOM VoIP Router fail due to a power outage, the life-line support and power relay over the ISDN bus, if activated, enable the connected telephones to continue to function.
- Enable spontaneous outside line access for ISDN and SIP users in order to keep the subscribers' telephone behavior as consistent as possible.
- The continued configuration and changes to the call routing table are carried out just as in the example 'Using VoIP telephony to extend the downstream ISDN PBX'.