1 I dont think it is very easy because you need certain skills and knowleges to speak freely even over the phone.
2 No, it is not correct. You can use a cell phone to call anywhere you want from any place that provide a cellular signal.
3 That is not correct. Moscow is the city with more that 10 million phone users , clearly it is not enough to have only 4 digits as a phone number.
4. I disagree on that. To book a trunk is the most secure way to get the service.
5. This is stupid. In that case people will struggle just to get to the telephone booth.
6 . This is not logical. Why should i give the calling person wrong information? Its better to tell him/her that they called the wrong number.
7. No , we dont do that . Usually we say << Hello>> just to make sure that we are heard / Also it s not very polite.