I do not know, but my first guess would be some sort of communications chip with embedded (possibly custom) military grade encryption/decryption used for voice

I do not know, but my first guess would be some sort of communications chip with embedded (possibly custom) military grade encryption/decryption used for voice communications in the field. The sort of thing where if you have the code of the day, you can listen to all the foreign military's voice communications in real time.