M1 has revealed the cause for a massive and ongoing network outage - an electrical incident leading to gas and water fire suppression equipment being triggered in a switching center.
The Singapore telco issued a statement explaining that at 3am on 15 January, a contractor installing a transmission system upgrade had caused a power incident that triggered the fire suppression system, causing the switch that covered the south-west of the country to fail.
At 9am on 16 January, the telco issued an update that migration to a working switch was progressing well with engineers working round the clock.
What is unclear is whether 2G services were also affected or if the networks were simply overloaded. M1 told its users to switch back to 2G but its Facebook page is full of angry subscribers complaining of no coverage at all, whether on 2G or LTE.
Judging from the comments it is also clear that many subscribers remain disconnected more than 24 hours after the event.