Your modem ID number, also known as a media access control address or simply MAC address, identifies your equipment as you surf the Web. The number can also be a valuable piece of information for requesting tech support, monitoring your modem's performance or just for maintaining your own records. You can find the number on the modem itself, through your operating system or by conducting an online diagnostic.
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On the Modem
If you have your modem at hand, all you have to do is turn it around to look up the ID number. You may need a magnifying glass if you have trouble reading small print, but the number is listed on the bottom or back of the unit, usually next to the unit serial number on a barcoded sticker. The MAC address is a 12-digit alphanumeric sequence and is usually preceded by the letters MAC or EA. If you're asked for the number by tech support, just give the 12-digit code. Some Motorola modems have 8-digit ID numbers listed after the letters SN.
MAC on a Mac
On an Apple computer, your modem ID number is listed in your network configuration. To access it, click on the Apple icon on the top left of your screen and click "System Preferences..." Click on the "Network" icon under Internet and Wireless. Click on "Wi-Fi" from the options on the left menu and then click on the "Advanced" button. Finally, click on the "Hardware" tab on the far right of the window; the MAC address will be listed on the first line.
Modem IDs in Windows 8
The easiest way to find your modem ID number on a Windows 8 machine is through the command line. On the Start screen, type "cmd" into the search field and press "Enter." Once the command prompt window opens, type in "ipconfig /all" to check your network and IP settings. Windows will generate all of your network information; your MAC address is listed after the phrase "Physical Address." Don't be confused by your IP address, which will have a different number of digits.
Find Your ID Online
Your MAC address is used as a unique identifier online and many Web pages that ask you to identify yourself will also be able to provide you with your ID number. The easiest and safest way to find your modem ID online is through an online modem speed test, which is also a good way to ensure your modem is functioning properly. Navigate to an online speed test (see Resources) and confirm your location for the testing page. Once the test is concluded, your modem ID and IP address will appear in the results.