I called the number back. It was answered by an actual person with an Indian accent, saying: "Thank you for calling Netgear support, may name is ...., may I have your case number." Since I did not call them before for support, I waited a while and then just hung up.
Everybody who receives unwanted solicitor calls should call them back, wait for a response, wait for a while and then hang up. This way, it will congest their phone lines and tie up their agents with unproductive work loads. If they are getting enough of such call backs, maybe they will stop their annoying practice!