How to make an scanner(radar) for find mobile number?(help me)

Hi guys
I will bulid a device to search or scan environs to find mobile number. I work by AVR microcontroller. I will to work my device like this softwere:

http://gallery.mobile9.com/f/1520656/

please help!!!

@ rozeh
i think it would be difficult to make and get working such type of device with simple components
also some network security also involved

Thanks majoka for answer!
please see vidoes of this link:

https://www.google.com/search?q=make+Mini+Wireless+Quadband+GSM+Spy+Phone+Surveillance+Device&hl=fa&client=firefox-a&tbo=d&rls=org.mozilla:fa:official&source=lnms&tbm=vid&sa=X&ei=pcHzUOaMOsuXhQfN0IDABA&ved=0CAwQ_AUoADgK&biw=802&bih=580

by this device you can hear call of personal(GSM System)!
the security of GSM is very low.
Can you help me?

@ rozeh
i never works on such type of spy

the video link you posted is only for audio surveillance not for scanning mobile numbers.. which i dont think its possible
what are your intentions

Yaeh!
it's just an Idea that I will to actualize!
can you help me?

its not possible to get mobile numbers of people around you...