The Frisco Police Department said Friday afternoon that all of its 911 phone lines were down.
Frisco police announced that service was restored at about 10 p.m. and all 911 lines have been repaired and are now working.
All 911 calls were rerouted to the McKinney Police Department during the outage, which is then transferring the calls to Frisco police.
The department instructed people who needed to call 911 to call the non-emergency line at 972-292-6010 until the issue was resolved.
Frisco police said they do not know the cause of the problem.