The CT1 and CE1 trunk cards perform the following functions:
•Terminate up to 12 T1 or 12 E1 lines
The CE1 trunk card provides physical termination for up to 12 E1 lines and connects to an external network termination (NT1) device, while the CT1 trunk card provides physical termination for up to 12 T1/Primary Rate Interface (PRI) lines, includes channel service units (CSUs), and connects directly to the telco network.
A framer removes framing and embedded signaling bits (or inserts them depending on the direction of the flow), and the framer CPU sends the data stream to onboard time division multiplexing (TDM) resources, which break out each call (DS0) and pass each call to an appropriate call termination resource. Digital or ISDN-originated calls are terminated onboard the CT1 or CE1 trunk card on High-level Data Link Control (HDLC) controllers, and analog modem-originated calls are passed over the dial shelf backplane TDM bus to an available modem resource. The system software controls modem and HDLC resource management.
•Respond to time-sensitive signaling
Each individual T1 or E1 port can be used as the system clocking reference. Each CT1 or CE1 trunk card can supply two clocks from any two of its twelve ports. You can assign priorities to these clocks, or accept the default values assigned by the software.