I find this helpful in orientating my staff on which is the proper communication media to employ whenever they need to communicate an issue.
I would ask them how urgent do you want to communicate it. Assess it’s importance and if it’s mission critical. Do you need to resolve it now? When you need to inform the user urgently, of course, you mustn’t use email. Call them, make a phone call, and inform them right away.
This pyramid is also used to remind them that a phone call is important to get answered, no matter even if you’re in a meeting and as long as you can hear that phone call, jump on it right away.
Let me know your views? Do you find this useful?