One of our C-class features a 3G communications module. Thus, the 3G connection is inoperable; nevertheless, 2G is still utilised for real-time traffic. Years ago, the internet connection was supposedly "switched off," but that's a different tale.
My wife may still monitor the status of our vehicle using the Mercedes Me app on her phone. This suggests that it can "speak" to the vehicle. Presumably, this is occurring over 2G. Seeing the vehicle's position and having the ability to lock it remotely are not supplementary features that we pay for.
To far, my sole experience with diagnostic tools has been with OBD-II plug-in devices.