Quad T1/PRI Card is a 10-position rotary switch allows the user to choose which of the four ports is selected for monitoring through the Bantam jacks (TXMON, TXIN, TXOUT and RXMON, RXIN, RXOUT). The LED labeled MON at each port lights to indicate, that port has been selected for monitoring. Only one port can be selected at a time. None of the ports is selected when the switch is set to the OFF position.The T1/PRI ports are configured as 100-ohm per port. For the Quad E1/PRI WAN card, the four ports can be configured as 75- or 120-ohm lines. The factory-set default is 120-ohm. Note that for the E1/PRI card you change the impedance using a software command.