You configure a channel on the SIM100 in the following way. Enter menu mode, scroll to "Configuration?" and press enter. Scroll to "Device Configuration?" and press enter. Scroll to the row containing SIM100 and press enter. Select instance press enter. Scroll until you find the appropriate instance and press enter. Select one of six channels and press enter.  Select a "mode?" disable, no end of line resistor, and end of line resistor press enter. Scroll to label and press enter. Press enter to edit the channel label. Using the available text categories you will be able to create your label. If you are satisfied with the label you have created select "Save and Exit" to complete your label. Press "Back" button five times to return to menu mode.