real-time detection of GSM terminals

[kahnoie]

I wish to know if it is possible to detect the presence of MS (or UE) in the vicinity (just to do a counter - count the number of MS passing through a gate). It could be useful in applications such as aircrafts and meeting rooms where mobiles should be turned off (or forbidden)

[kahnoie]

Only the following happens in idle-mode
PLMN selection (not useful)
Cell selection
Cell reselection
Location updating - normal and periodic
IMSI attach/detach

Only the foolowing channels are used on the UPLINK
- RACH (not useful)
- SDCCH
- FACCH
- SACCH

The MEAS reports are sent but only in dedicated mode. So is there a way to detect MS in idle mode without adding additional source of noise?