An outage of 5,700 analog telephones struck Stanford’s campus on Wednesday, affecting 10 percent of campus telephone users and lasting until Thursday evening.

Governor’s Corner, Bonair Siding and the Stanford Healthcare Center were most heavily affected by the outage, which also disrupted some campus elevator lines, fax machines, point of sale lines and alarm circuits. The Door Kings service used to ring in guests from room phones was also disrupted during the outage.

While analog phones were affected, phones operating on Voice over Internet Protocol (VoIP) systems were not, according to an AlertSU notification sent on Thursday morning. The cause of the outage remains unclear. University IT (UIT) has not responded to The Daily’s request for comment.

Analog phone services carry signals via copper wire landline connections, whereas VoIP services rely on Internet connection. Though analog — or plain old telephone service — is used less than VoIP, analog telephones remain present in many Stanford buildings, including student dorms.

“We apologize for the inconvenience that this outage caused,” UIT wrote in a Thursday email announcing the outage’s conclusion.

Contact Brooke Beyer at bbeyer ‘at’ stanford.edu.