- "call someone in" には「協力を求める」という意味が。（enlist someone's aid or service ※enlist=協力を要請する／to call on the special talents, abilities, or power of someone or something. ／to request a consultation with a specialist in some field. The person called probably will not "come in," but will work at another place.／to demand that someone come to do something specific )
- They had to call a new doctor in. Yes, they had to call in a specialist.
- We will have to call a heart specialist in for a consultation.
- We called in another specialist for an opinion.
- The mayor called in the police to provide extra security for the conference.
- I can't afford to call the plumber in every day!