With mobile phones so prominent these days there is becoming less need for a land line connection. A GPRS unit can be installed and there is no need for any ongoing phone call charges or the need for a landline phone plan to simply have back to base monitoring. Your only ongoing fee is the back to Base monitoring charge. No plan fees, no phone call fees, just your monitoring.
With NBN connections you do not need to worry about phone line reliability and do not need to worry about being reliant on power to ensure you have back to base monitoring at all times.
GPRS units cannot be interfered with by a potential intruder from outside of the premises. The intruder would firstly need to enter the building, setting the alarm off and as a result alerting the control room of the breach, then have to locate the unit to have any effect on the system.
GPRS units have never been more affordable than they are today. With the increase of mobile phones being manufactured, GPRS units are in larger supply now and the cost of parts have decreased considerably.