- Internal telephony with ISDN and SIP telephones and SIP softphones.
- External telephony with VoIP terminal equipment via the SIP provider with backup over ISDN.
- External telephony with ISDN terminal equipment in the PBX. Depending on the functionality of the ISDN PBX, ISDN terminal equipment can also use the SIP lines in the R&S®NC VoIP router.
- Accessing internal terminal equipment (ISDN and SIP) via the MSNs.
- Calls to emergency and service numbers via ISDN.