A "deliberate and malicious cyberattack" against a major mobile operator in Portugal left millions of users without internet, television, or phone access, the firm said in a statement on Tuesday.
"We were faced with an abrupt interruption, and all our services were affected," Vodafone Portugal CEO Mario Vaz told the media on the attack that was "intended to cause damage and disruption."
"We were victims of a terrorist and criminal attack," he added.
Hackers hit the telecom's services on Monday at 2100 GMT, with the company first able to restore phone calls and minimum data on its 3G network.
By Tuesday morning, text message, television, and internet services were also back online. Nearly 20 hours later, the company continues to work to restore the services that remain, including 4G and 5G.
Vodafone said it has no evidence that the hackers stole customer data.
The company provides internet access to 3.4 million Portuguese homes and companies and has 4.7 million mobile customers, according to Vodafone.
Portugal's population is just over 10 million.
Portuguese police have announced an investigation into the massive cyberattack. Whether it was part of an extortion attempt has yet to be confirmed or denied.
The attack on Vodafone Portugal came just a day after police told local news agency Lusa that an investigation was underway into "a possible cyberattack" against the Portuguese media conglomerate Cofina, which publishes some of the country's top newspapers.
The country's parliament is also investigating a possible hacking incident against its own website during the national elections on Jan. 30.
The hacker group Lapsu$ claimed it had "stolen sensitive information" on election night and has been blamed for disrupting services of the media group Impresa, which sent fake news alerts out to its customers after it was hacked last month.
