Mobile Phone Signal Flash Light 3-12V - not working. Circuit viable?
The circuit itself might work.

In DC Q2 is on, its collector is low, Q3 is off and the led is off. Q1 is in AFR but the DC value of its collector does not affect the circuit.

When you receive a call some current is induced in the antenna. Low frequency components are shorted to ground by the coil, while higher frequencies can possibly bias the diode and steal some base current from Q1. That is strange because it seems to me that Q1 gets turned more off, Q2 more on, Q3 more off, no luck with the LED. I think the diode should be reversed, and you can even omit C1.

I also think that some capacitor in parallel with L1 might help, the resonant frequency should equal the carrier frequency you want to detect.