[https://www.law.cornell.edu/cfr/text/47/4.5] Specifically, for 911 facilities, an outage is considered to exist whenever one of the following conditions exists:
- There is a loss of communications to PSAP(s) potentially affecting at least 900,000 user-minutes and: The failure is neither at the PSAP(s) nor on the premises of the PSAP(s); no reroute for all end users was available; and the outage lasts 30 minutes or more; OR
- There is a loss of 911 call processing capabilities in one or more E-911 tandems/selective routers for at least 30 minutes duration; OR
- One or more [landline] end-office or [cellular] Mobile Switching Center (MSC) switches or host/remote clusters is isolated from 911 service for at least 30 minutes and potentially affects at least 900,000 user-minutes; OR
- There is a loss of ANI/ALI (associated name and location information) and/or a failure of location determination equipment, including Phase II equipment, for at least 30 minutes and potentially affecting at least 900,000 user-minutes (provided that the ANI/ALI or location determination equipment was then currently deployed and in use, and the failure is neither at the PSAP(s) or on the premises of the PSAP(s)).