1, the subaudio setting is incorrect, please check the transceiver frequency and subaudio;

2. The interphone hardware is physically damaged, so it is necessary to contact the after-sales department for detailed inspection.

Sub-audio: CTCSS (Continuous Tone Control Silencing System) and Continuous Voice Control Silencing System, commonly known as sub-audio, is a technology of adding frequencies lower than the audio frequency (67Hz-250.3Hz) to the audio signal and transmitting them together.

Because its frequency range is lower than the standard audio, it is called secondary audio. After the interphone demodulates the received intermediate frequency signal, it filters and shapes the secondary audio signal, and then inputs it into the CPU, and compares it with the CTCSS frequency set by this machine, so as to decide whether to turn on the mute.