cellular activity sensing

Hello,

I'm looking into building a cellular activity detector which would work within a radius of minimum 5 meters.
Is there exist an Arduino-compatible mobile transmission sensor that can sense the presence of an activated mobile cellphone? Also, is there a way to detect the presence of idle cell phones? (i.e. cellphones that are not active, making a call or connected to WiFi, etc.)

Thanks,
K.

Look here: Mixed-signal and digital signal processing ICs | Analog Devices
Page 110. Basically, OPA could be any, as it amplifiers DC, but ones with low offset voltage is preferable.

Also, is there a way to detect the presence of idle cell phones?

I'm sure it's possible, as any cell has uCPU + gLCD running, that good RF scanner can detect within 5m or even more.