NetworkFirst is a Voice Over IP switch (VoIP) that interconnects incompatible radio systems in the same way that AT&T interconnects telephone subscribers, except that NetworkFirst is connected into each agency's radio system rather than their telephones; and interoperability is instantaneous. Each participating radio system outputs its audio into a NetworkFirst voice gateway that converts the audio into IP data packets. The packets are then routed over a private IP network into a NetworkFirst Switching Center. In a field trial, 13 incompatible radio systems of local, State, and Federal agencies were patched into a Network First Switching Center established for the trial. The city's police, fire, and emergency medical service (EMS) agencies remapped their radio channels to make room for three NetworkFirst talk groups. The benefits were immediate, as State troopers using Motorola radios began talking to DPD officers on M/A-COM portables. The trial deployment's reach was expanded to make it permanent. Still, although NetworkFirst can enable communications across incompatible radio systems, it cannot solve all of a first responder's communications problems. Radio coverage problems, equipment issues, and other challenges must be resolved when implementing a NetworkFirst system.