Real time monitoring is totally automated these days. For example, I have a friend who works for the AG in King county. Whenever a person of interest makes a phone call, and a warrant is in place, they automatically get a call on thier mobile phone and have the option to listen in on the call or not. just press 1. Thats only where these types of service start.
Some indications of possible cellphone surveillance occurring may include a mobile phone waking up unexpectedly, using a lot of the CPU when on idle or when not in use, and the circuit board of the phone being warm despite the phone not being used. Thats how you might know your mic or camera are being used, even whle the phone appears to be off.