Yes, your calls would be traveling over an encrypted tunnel to the carrier instead of the (simulated) cell tower, thus preventing the Stingray/site-simulator from carrying and listening in on your call.
However, it would not stop someone from listening to the call at any point over the rest of the path since the call itself is not encrypted, only the transport between the carrier and your phone.
However, it would not stop someone from listening to the call at any point over the rest of the path since the call itself is not encrypted, only the transport between the carrier and your phone.