That's far from ideal, but country codes in phone numbers are also always prefixed, so a phone number in country code 999 would never start with that number, it

That's far from ideal, but country codes in phone numbers are also always prefixed, so a phone number in country code 999 would never start with that number, it would either be +999 [something] on a smartphone for example, or the old school equivalent 00 999 [something].