Dell Precision M20 User Manual page 77

If you ordered the optional modem at the same time that you ordered your computer, the modem is already installed
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions in the Product Information Guide.
1. Follow the procedures in "Before You
2. Turn the computer over and release the captive screw from the modem cover.
1 captive screw
3. Place your finger under the cover at the indentation and lift the cover open.
1 screw
2 modem
3 coin-cell battery
4. If a modem is not already installed, go to step 5. If you are replacing a modem, remove the existing modem:
a. Remove the screws securing the modem to the system board, and set them aside.
b. Pull straight up on the attached pull-tab to lift the modem out of its connector on the system board, and disconnect the modem cable.
5. Connect the modem cable to the modem.
NOTICE: The connectors are keyed to ensure correct insertion. If you feel resistance, check the connectors and realign the card.
6. Align the modem with the screw holes and press the modem into the connector on the system board.
Begin."