Does the ISDN port provide ISDN line power?
It depends on the model. SmartNode 4634 and 4638 can be software configured to provide line power to terminals. Smart-DTA always provides line power. All other SmartNodes don’t provide line power. However, they do forward line power received on the TE port to the NT port. So if a public ISDN-PSTN line is connected to the TE port and this line provides power then the power will be available to the Terminals connected to the NT port of e.g. the SN4552. Optionally if there is no line connected to the TE port you can install the PM-BRI-EXT S-Bus phantom power supply to power Terminals connected to the NT port. An ISDN S-Bus can provide up to 8W of 40V DC power. Many ISDN Phones draw their operating power from the ISDN S-Bus. This is usually not the case for PBX systems which are typically local mains powered. Check the technical specifications of your ISDN terminal equipment to find out if line power is required.
