Built-in 85 Decibel Siren Voice Prompts guide you through installation. Cellular Technology: No Phoneline needed for 24/7 alarm monitoring! However, if you want redundancy, you can also plug in your phoneline or use an internet connection. 41 Sensor Capacity: Get all the sensors you need to protect any home, large or small. Backup Battery lasts up to 24 hours during a power outage. Base Station will recharge them once the power is restored to your home.