from the seller's web site...
The PLM-JNGSMTX08 Micro GSM Listening Device is the pinnacle of GSM listening technology packed into an incredibly small package just 43 x 34 x 17mm. Just insert any SIM card, call the number and you will hear exactly what is going on in your absence.
UK customers can track its location at any time via the internet making it a compact dual purpose surveillance device. Supplied with mains charger and protective carry case. This is the ultimate micro miniature listening device! (more)
Why do I mention it?
So you know what you are up against.