I am getting the unlock or un-secure lock image on my Nokia phone when ever I call.
Most GSM operators do encrypt their subscribers' communications, but some may choose not to do it, and in some countries, like India, they may even be required by law not to use encryption.
Another very senior expert told us: “False base stations are always possible on GSM. It does not surprise me. Of course, encryption can be turned off by the operator, or by the State such as China or India. It does not happen on 3G or LTE if you are using mutual authentication.”