As you can see by the picture above (OK...we did not hire the world’s best photographer), modems normally have two phone connections. Some modems will have other connections such as audio plugs but for most this is what your modem will look like. Modems use CAT3 (Catagory-three) type cable. This is normally what you have in your home or office for connecting your phones. One connection will normally have LINE or IN labeled next to it and the other should have OUT or PHONE labeled on it. You connect the phone line from the wall outlet to the connection labeled LINE or IN.  Use a separate phone cable and insert it into the PHONE or OUT connection.  You may then plug the OUT connection to a regular phone. Modems support passthrough, that means that even if your computer is off, you can still use the phone as usual. Although the links below should help you they are by no means all the problems that are associated with modems, just the most common.  Click on a link below for modem help relevant to your problem.