Approximately 109 million customer accounts were affected in the breach which mostly occurred in 2022,
At least 7.6 million existing AT&T account holders and 65.4 million former users hit by the breach, the company says.
Questions swirled after four cables were cut; some observers say it may be the Houthis, others say it was an accident.
The government temporarily suspends mobile phone services as it holds the parliamentary and provincial election.