Customer FAQs Discover answers to the most frequently asked questions from ADT customers with the click of a button. 1. How does the VoIP/Digital Phone Service work with my alarm? When an alarm from home security systems is triggered, these companies use the Internet connection rather than traditional phone lines to provide home phone service. Although these technologies provide a form of telephone service, there may be differences in their range of features and reliability. Features and service reliability may vary depending upon your VoIP or other non-traditional telephone service provider. You should check with your phone provider to understand any disadvantages or limitations of their service. You should also call ADT if you change from a traditional phone line to any form of VoIP service. In some cases, a cell radio may need to be installed for alarm communications.