The Cisco 5814 dial shelf contains 14 slots (numbered 0 to 13 on the backplane) and can support as many as 10 modem cards, 2 T3 or 4 T1 trunk cards, and 2 dial shelf controllers (DSCs). Slots 12 and 13 in the dial shelf are dedicated slots for the DSCs. Metal guard pins on the backplane module prevent you from installing any other type of card in these two slots. The modular chassis supports online insertion and removal (OIR) and redundant power and includes environmental monitoring and feedback control.The dial shelf contains CT1/CE1 or CT3 Primary Rate Interfaces (PRIs) that terminate ISDN and modem calls and break out individual calls from the appropriate telco services. Digital signal level 0 (DS0) or ISDN calls are terminated on the trunk card High-Level Data Link Control (HDLC) controllers, and analog calls are sent to modem resources on the modem cards. As a result, any DS0 can be mapped to any HDLC controller or modem module. You can install multiple ingress interface cards of like or different types, which enables you to configure your systems as fully operative, port redundant, or card redundant, depending on your specific needs.