The wireless micro audio bug is a composition of oscillator transmitters and receiver. No need gsm card and zero configuration. It works on fixed special FM freuqncy. Thanks the special signal transmission encryption, other receivers are not listening to the audio signals. Due to excellent audio collection, you could here the voice (audio signals) clearly after turn on both transitter and receiver. The record socket allows you connect receiver to any digital audio recorders through 3.5mm jack and take record valuable information. Since comes with two different audio signal transmitters, you could be able to use VHF-TA2 to monitor voices from telephone conversation and locations. Large Phones Features of VHF-TA2 Audio Bug No software nor configuration requested. Frequency is fixed by the quartz oscillator. Ultra-compact designs offers optimum performances. Easy to hide. Outstanding audio collections. Clear voice heard through earphone and recordable. Two channels surveilance available, telephone conversation and location monitor. What you will get for a full set of VHF-TA2 Audio Bug One pc Oscillator Receiver One pc telephone audio transmitter One pc regular audio transmitter One pc travel charger with retractable use cable Two pcs string antennas for regular transmitter and user's guide Cautions for use a VHF-TA2 correctly I. Trasmitters Available battery models are LR44 alkaline battery, PR44/13PH lithium battery or CR1/3N/DL 1/3N button cell. Open the case of trasmitter and load battery in bottom of case. Screw string antenna into antenna socket of regular transmitter and stretch out Turn on power switch and begin to transfer audio signals II. Receiver Extend earphone since it is a part of antenna of receiver Turn red color switch to right side until heard "beep" voice Remember to switch off power switch after use Open lid and change battery