[saycheese]

What based on the use case provided [1] would the the number one most likely edge-case and what is the most common solution to it?

Making a claim without constructive supporting points is usually not useful and worst appears you may know nothing other than how to cause problems seeding doubt.

[1] Use-Case: Create a virtual number on Twilio and whenever someone calls, a list of real numbers will be tried sequentially. You can set up opening hours. If nobody answers, a voicemail is recorded and sent to you by email.