This example shows how to configure a LANCOM when the ISDN telephones used unit now are to be enhanced with VoIP telephony. The external MSNs '555 555 1' and '555 555 2' on the ISDN bus at the NTBA were used for two ISDN telephones until now. The LANCOM will now be switched between the public ISDN connection and the internal ISDN bus connected to the ISDN telephones.