Send a message to the doctor during the break, and answer it without calling back.

Hello, I'm glad to answer your question.

Doctors have great responsibilities, great intensity and relatively precious rest time. If he doesn't reply to the message, he may not see it or really have no time to reply. And the phone will be connected immediately, because it is more efficient and time-saving than sending messages.

Thank you for your trust. The above is my reply. I hope I can help you and wish you a happy life ~