"KLM" wrote in message
...
Why not include a circuit in every cellphone that will cause the
answer bell to ring when anyone carrying a cellphone crosses one of
these interrogators. Maybe have the circuitry activate a different
ring tone or ring pattern from the normal call ring. Its extremely
short range and won't interefere with normal cellphone use.

Simple - again, the strong likelihood of interference with cell phones
AND other legitimate services. Plus the rather obvious fact that it
won't achieve the desired goal; once these things were placed into
service, it would be trivially easy for a "cell phone bomber" to disable
their phone's ringer. Or to cause a dummy ringer (the one that doesn't
have to do with the bomb) to go off and thus defeat the security.

You really should learn a bit more about how these things work before
proposing supposed "solutions" to the supposed "problem."

Bob M.