The VM-3 can be installed into a mobile or portable two-way radio to record incoming radio transmissions. When the VM-3 sees a busy indication from the radio or detects VOX it will start recording the received audio. When the busy indication goes away for a programmed amount of time, the VM-3 will stop recording.
One of the main benefits of the VM-3 voice storage module is that the recording blocks are not set in stone like most other voice storage modules. If the radio transmission is only 5 seconds in length the recording block only uses 5 seconds of the 180 seconds. Some competitive units have recording blocks of 30 seconds. If the recording is 5 seconds the other 25 seconds are lost, thus greatly reducing the actual total recording time.