Wireless systems are powered by battery. The control unit has a built-in indicator to show when batteries needs replacing. Having a power source independent of your home's power grid increases a system's reliability. When electric power is out at your house, it is still being monitored and protected.
Microwaves, cordless phones, wireless computer systems and plaster walls can all interfere with your wireless security system, making it less effective and reliable. Strategically positioning your control box can help prevent these issues.
Wireless systems can not connect to a telephone landline and criminals could disable your system before it can even signal something is wrong. Some companies remedy the phone line issue by making the system compatible with cellular technology, enabling you to connect your cell phone to the system. The effectiveness issue comes mainly in systems that are marketed as all-in-one units. Hybrid units do not have this drawback.