Well, I hate to suggest that teachers have to count off -- I always feel like it's better to just make a note first without deducting points, if it's not something they've specifically learned in the textbook. Or review the example next time in class.

However, no, (3) isn't idiomatic in my experience. And even (2) is rather curt, maybe more in the top-down style of a boss, or a man speaking to another man, than a polite co-worker or an employee speaking to a client or customer. I would stick with 'This is ...' as the default, especially for beginners or intermediate learners.

Yes, there should be several threads in the archive (Suche in allen Foren) where we've discussed telephone etiquette, though it's changing as more and more people have caller ID.

As I understand it, in German-speaking countries it was once traditional for the person answering the phone to identify themself to the caller, even at a private residence. In the US at least, people once might have said 'Smith(s') residence,' but now that most calls are garbage, that's much less common.

(In fact, now that most calls are garbage, many residents let all calls go to voice mail or an answering machine, with a screening message like, 'This is 555-234-1212. Please say your name or leave a message at the tone.')

In English, only businesses identify themselves when they answer, e.g., 'XYZ Company, this is Johann Hirschkuh, how may I help you?' Private households say 'Hello' and wait for the caller to say 'Hello, this is Jane Doe at XYZ Company. May I speak to / with Mr. / Ms. Smith?'