Abusive and difficult callers
Most businesses have a handful of these a year and some have them weekly. They are treated as an unfortunate part of front-line work, which quietly means somebody on your team is absorbing them as a condition of employment. That is worth examining rather than accepting.
Tell the two apart first
A caller who is upset because something went wrong is not the same as a caller who is abusive. The first deserves patience, a person, and a remedy — they have a grievance and are expressing it badly. The second is directing hostility at whoever answered, which is not about the appointment at all. Conflating them produces both bad outcomes: real complaints get treated as aggression, and aggression gets rewarded with an apology.
What should happen on the call
Whoever answers should know, explicitly, that ending an abusive call is permitted and supported. Most people will not do it unless told.
Matching tone produces something that gets recorded and shared, and you will be the one explaining it.
If there is a real complaint buried in it, that part deserves a proper route — later, and calmly.
Not to intervene necessarily, but because a pattern from one number is something you can act on.
Where software genuinely helps
Not by handling abuse well — it is not pleasant for anybody to be shouted at and there is no clever answer. It helps because nothing is being absorbed by a person who then carries it into their next three customers. An assistant answering the first thirty seconds of a hostile call means the human who eventually takes over does so knowing what is coming, or does not have to take it over at all.
Afterwards
A record matters here more than almost anywhere. Repeat behaviour from one number is a thing you can take to your provider or, past a point, to the police — and both will ask when it happened and what was said. Relying on your staff to remember is both unfair and useless. And say something to whoever took the call, the same day; being asked about it is most of what makes it bearable.
Frequently asked
Distinguish upset from abusive first. Whoever answers should know explicitly that ending an abusive call is permitted, should not match the tone, and you should know it happened.
No, and conflating them causes both failures — real complaints get treated as aggression, and aggression gets rewarded with an apology.
Not better, but nobody on your team absorbs it and carries it into their next three customers. Whoever eventually takes over does so knowing what is coming.
Keep the record — repeat behaviour from one number is something your provider or the police will ask dates and details about. And check on whoever took the call the same day.