IMDA fines Singtel S$1 million over October fixed voice outage that disrupted emergency calls

On 11 December 2025, the Infocomm Media Development Authority (IMDA) announced a financial penalty of S$1 million on Singapore Telecommunications Limited (Singtel) following a widespread fixed voice outage that occurred on 8 October 2024.

The service disruption affected approximately 500,000 residential and corporate users, with critical implications including failed access to emergency hotlines, government agencies, healthcare organisations, and local banks.

According to IMDA’s official findings, the disruption stemmed from a fault in Singtel’s internal system configuration. Singtel had hosted two separate virtualised firewalls—one for its fixed-line voice system and another for the monitoring system used for home broadband and Pay TV—on shared hardware.

When the monitoring system experienced an unusual spike in traffic, its firewall lacked adequate filters to prevent system overload. This overwhelmed the shared memory resources, leading to a failure in the voice system’s firewall, which began to operate intermittently.

The situation was exacerbated when the automatic failover mechanism—intended to seamlessly redirect voice traffic to a backup system—did not fully activate. As a result, calls fluctuated between functioning and non-functioning systems, with many being dropped.

Full restoration of services was only achieved after Singtel manually redirected all traffic to the unaffected backup system.

IMDA’s investigation concluded that the outage was not the result of a cyberattack. Instead, it was deemed a preventable incident within Singtel’s operational control. These findings were corroborated by independent external consultants appointed to review the failure.

The scale and nature of the disruption significantly impacted public safety, particularly the brief inaccessibility of emergency call services 995 and 999. Public warnings were issued through the Singapore Police Force and Singapore Civil Defence Force's (SPF and SCDF) social media accounts around 7:00 PM, confirming that normal call operations had resumed.

Earlier in the day, user complaints had surfaced on social media and Downdetector, highlighting widespread landline issues. By 5:07 PM, Singtel reported that engineers had isolated the problem and were deploying recovery measures.

Critical services affected included healthcare providers such as KK Women’s and Children’s Hospital, the National Cancer Centre, and Changi General Hospital. Singapore’s major banks—DBS, UOB, and OCBC—also reported temporary hotline disruptions.

In determining the S$1 million penalty, IMDA cited the broad scale of the impact, the delay in service restoration, and the serious risk posed to public safety.

Following the incident, Singtel implemented remedial measures. These include the physical separation of hardware for voice and monitoring systems, as well as the introduction of a new intervention mechanism to prevent traffic alternation during system failovers.

Speaking in Parliament on 11 November, Senior Minister of State for the Ministry of Digital Development and Information, Janil Puthucheary, explained that the failover failure occurred between two geographically separated systems meant to provide redundancy. He confirmed that the incident was not linked to cyber threats, sabotage, or hacking.

Dr Puthucheary reiterated IMDA’s role in ensuring high performance standards for key infrastructure providers and confirmed that Singtel was mandated to prioritise recovery of essential services during the outage.

Minister of State for Home Affairs, Sun Xueling, added that during the service failure, alternative emergency contact methods—such as SMS numbers 70995 and 70999 and the SGSecure app—were activated. She stated that future efforts would focus on increasing public awareness of these alternatives.

In response to the incident, IMDA has instructed all other key telecommunications providers to examine their network configurations for similar vulnerabilities. These service providers must report their findings and remediation plans to IMDA, which will independently validate the changes.

IMDA emphasised its commitment to ensuring reliable telecommunications infrastructure, particularly systems that underpin emergency services and public communications.

Under the Telecommunications Act, IMDA may impose penalties of up to S$1 million or up to 10% of a company’s annual turnover for lapses. It has warned that strong enforcement measures will be taken should similar disruptions occur in the future.