Abstract: The apparatus (101) and method provide for data transmission capability on bonded data channels of a communications network (104), such as an integrated services digital network, utilizing a single serial communication controller ("SCC") for the bonded data channels. The apparatus (101) includes an interface transceiver (210), interface circuitry (220), and an integrated multiprotocol processor (200). The integrated multiprotocol processor (200) contains an SCC (420) which may be utilized for data transmission on bonded data channels, with other SCCs (430, 440) available for use on other channels. The apparatus and method provide for proper data alignment of primary (or master) channel data and secondary channel data on the bonded channels, through the same SCC, through utilization of a predetermined information pattern transmitted in a loopback mode (810, 820) of the interface transceiver (210), to the receiver of the SCC (830).