Workers were fixing the server that went down within the last week. During that work, which started on Tuesday night and continued into the morning hours, it was anticipated that there could be a brief outage, and officials say that is what happened.
The work is completed for the time being, as they do not do maintenance at peak times. When work resumes, there will be a possibility of another brief outage.
During these outages, workers use pen and paper.
The EMS CAD System is 30 years old and being replaced as part of the 911 overhaul.
The giant 911 system is in the process of being upgraded at a total cost of $2 billion, including a new back-up center.
The piece that failed Monday was EMS dispatch, a system from the 1980s that's scheduled to be upgraded in 2015.
There have been glitches in other, newer parts of the system that have prompted criticism.
Fire department workers were running diagnostic tests to determine why the system was having problems.