The TN570B provides an interface between the TDM bus and packet bus, and fiber optic links interconnecting cabinets
Used in a Port Network (PN) between a PN and another PN in a direct-connect system and a PN and an SNI in a switch node carrier in a CSS-connected system
Provides control channel applications and time-slot interchanging between the PPN and EPNs
Used when ISDN-BRI and/or ASAI is connected in an EPN
