Restrictions for Configuring NFAS with D-Channel Backup
Restrictions are described in the Restrictions for Configuring ISDN Voice Interfaces, page 4. In addition, the following apply:
•NFAS is supported with only a channelized T1 controller and, as a result, is ISDN PRI capable.
•The router must connect to either a 4ess, dms250, dms100, or National ISDN switch type. Table 47 shows applicable ISDN switch types and supported NFAS types.