The Network Side ISDN PRI Signaling, Trunking, and Switching feature enables Cisco IOS Software to replicate the public switched network interface to a PBX that is compatible with the National ISDN (NI) switch types and European Telecommunications Standards Institute (ETSI) Net5 switch types.
Routers and PBXs are both traditionally Customer Premises Equipment (CPE) devices with respect to the public switched network interfaces. However, for VoIP applications, it is desirable to interface access servers to PBXs with the access server representing the public switched network.
To configure the Network Side ISDN PRI Signaling, Trunking, and Switching feature, ensure that the selected access server is in this condition:
The T1 or E1 controllers are operational and configured for ISDN PRI.
The D-channel interfaces are operational and configured for ISDN PRI.