We use the Alula Wireless communicator. Your alarm needs a way to call out to the monitoring station whether it be a phone line or a cellular communicator. A cellular communicator is a device hooked up to your control panel instead of a traditional phone line. The advantages are no phone line can be cut, it includes an application for your cell phone or tablet. You can access this to arm and disarm your system as well as long as you have internet. You can also sign onto a computer and do this as well.