UK regulator Ofcom has launched an investigation into BT and Three over outages that both telcos suffered during the summer.

Three suffered a network outage in June that left thousands of customers unable to make calls.

A month later, BT and EE also had a significant network outage, which impacted calls to the emergency services between July 24-25.

Those outages have prompted Ofcom to investigate the incidents. The watchdog stated that both telcos notified Ofcom of the outages at the time.

"Our investigations will seek to establish the facts surrounding these incidents and assess whether there are reasonable grounds to believe that BT and Three have failed to comply with their regulatory obligations," said Ofcom in a statement.

BT has confirmed it will fully cooperate with Ofcom's investigation.

The telco was fined heavily last year after a technical fault heavily impacted its ability to handle emergency calls in 2023. In total, BT Group was slapped with a £17.5 million ($23.4m) fine.

During that particular incident, Ofcom concluded that BT was "ill-prepared to respond to a catastrophic failure of its emergency call handling service" during a period that lasted for around 11 hours.

Three has also previously been fined for its handling of connecting customers to the emergency services. In 2017, the telco was fined £1.7m ($2.28m) for an incident in 2016.