When making a call from 30,000ft to prepare ground staff for arrival, several regional airports within the same geographical area might get the same message. By using DTMF signals enabled by the IPR110+, different user groups can be created. This enables selective calling to the individual airport or user groups within the airport.
By implementing this system, the regional airline can improve their efficiencies as staff no longer need to listen to radio traffic not directed to them. In addition, the IPR110+ is able to be connected to legacy equipment for ease of transition.
See the full Application Note here.