The DMTH4 integrates telephone lines, video codecs and external audio sources into the digital bus structure of DM Series processors so these sources operate as though they are another microphone or audio input in the sound system. The unit is much more than just a telephone interface. Instead, it is a complete DM Series digital matrix processor, with a 3-in/24-out digital matrix, automatic mixing and comprehensive signal processing on every input and output. In essence, it simply connects to telephone lines, video codecs and external audio sources instead of mic/line inputs and outputs and integrates seamlessly with DM Series matrix processors.