Alarm systems used to send signals down the copper phone-line to the alarm monitoring service. But there are now other ways they can communicate.

IP monitoring

Most alarm companies now offer IP monitoring - this lets them monitor the alarm through your internet connection, using a small device connected to your alarm and also to your router or modem.

Already have an alarm? Then your alarm company can tell you if your existing circuitry is suitable for IP monitoring. If so, the device you need is likely to cost from $100 to $200 - although some alarm companies will provide it free. Putting in a new IP system should cost roughly $100 more than a traditional landline system. That’s according to one major alarm company, AlarmNZ.

Monthly IP monitoring costs should be the same as for landline-based monitoring.

Tip: Alarm companies recommend you also install an uninterruptible power supply (UPS) unit. This is a low-voltage backup power unit in case the power goes out; it runs on batteries and can cost from $100 to $300 depending on the features. Your alarm company should be able to supply this. Even if you don't have an alarm, UPS is recommended if you have broadband as it'll keep your phone working if you're using VoIP (Voice over Internet Protocol) calling.

Cellular monitoring

Another method is cellular monitoring. This is where a wireless device and SIM card in the alarm panel sends a signal to the alarm company through the mobile network.

There are two types of cellular monitoring: GSM Voice and GPRS/3G data.

GPRS/3G data uses the mobile broadband network, so its coverage is more limited than GSM Voice's, especially in rural areas. (GSM Voice uses the mobile phone network.) GPRS/3G data's monthly charges are fixed whereas GSM Voice's are per call - which is cheaper will depend on how often your alarm system is likely to make a call.

If you want cellular monitoring, you don't have to start from scratch - you can use your existing circuitry. But with a wireless device costing up to $350 and the alarm panel another $300, cellular monitoring is more expensive to convert to or set up than IP monitoring. And cellular monitoring will also cost more: between $5 and $20 extra per month, depending on which mobile network you’re with and the type of plan you're on.