Patient calls surgeon's professional number, and their office switchboard forwards it to the surgeon from the "Incoming Patient Call" number, which is whitelisted in the surgeon's phone.
Why would a patient be dialing their doctor directly, anyway? Any reason I can think of would still allow for the physician to whitelist that person in their contact list. Most of the time, the doc would probably want the call recorded and transcribed for the medical records, and also billed to the patient's insurance as a patient consultation. A direct call couldn't do that without an app to help out.
All of the "business" contacts in my phone are for the main dial-in number for a company. I don't need to dial direct to Joe the mechanic or Trudy in accounts receivable or Jean-Pierre on the help desk. The business's automated switchboard can enforce business hours and vacations, and still connect me to whomever I need to speak to for that call. And if an employee needs to contact me, they don't even need to know my phone number. They can speed dial the company employee outbound number and punch in my work ticket number, and be connected automatically, from the company number. The identity authority is delegated to the individual business, instead of the proven-untrustworthy phone company.
It isn't that difficult for a business to set up their own call-management server these days.