
Explanation:
Box 1: DateTime expiration = context.CurrentUtcDateTime.AddSeconds(90); The user has 90 seconds to respond with the code they received in the SMS message.
Box 2:var timeoutTask = context.CreateTimer(expiration, cts.Token);
Create a timer.
Box 3: if(!timeoutTask.IsCompleted)
All pending timers must be complete or canceled before the function exits.
References:
https://github.com/Azure/azure-functions-durable-extension/blob/master/samples/precompiled/PhoneVerification.cs