Within the platform short numbers are used for extensions and dial plans. Normally these numbers can be assigned freely, however, there are certain restrictions with regards to emergency and special numbers. For these numbers validation rules are in place to ensure these numbers cannot be used as an internal number.
Since users should always be able to make a call to emergency numbers, these numbers will be automatically whitelisted and are no subject to the call limits. Emergency numbers are always reachable even when a company has reached their limits.