Locate the alarm system's panel and check to make sure it has power. Typically, it is near the front door; it may be in a bedroom. Press a few buttons and look for lights. If you hear noises or see buttons light up, your system has power. If it does not have power, proceed to Step 2. If it does have power, proceed to Step 3.
Power up your alarm system. Many times, previous owners of an alarm system will power it down before selling their home. If this is the case, you need to locate the alarm system's power station. This is typically installed in a basement or crawl space. It should be in a box similar to the picture shown in References 3. To reconnect the power, plug the outlet back into a wall socket once the panel is located.
Retrieve the alarm panel's registration code and note the brand of the alarm system. This number is typically located at the bottom of your alarm panel. The brand of the alarm system may be noted on the front of the panel or near the registration number. See References 3 for guidance. Brands include DSC Power 1616 or GE Caddx.
Choose an alarm monitor. You can choose a local company from your area or a nationally based alarm company, such as ADT or Broadview Security. Make your decision based on services offered and the rates of the company.
Call the security company of your choice. Relay that you want to activate your system. You will probably need the tell them the alarm system's registration code as well as the brand of the system. Follow any other instructions given (such as payment information and alarm code information).
Arm and disarm your system. Once you have relayed all of the information to the security company, you will probably be given an activation code for your system. Use that code to arm and disarm your system. Simply punch in the number and press "arm" or "disarm" (or similar language). Test the system prior to relying on it. Call your security company for troubleshooting issues.