Photo: Mawardi Bahar / EyeEm / EyeEm / Getty Images
The US's largest phone network, AT&T, experienced a major outage, prompting warnings from emergency services and advice from companies to use Wi-Fi calling.
The outage began early on Thursday, with AT&T working urgently to resolve the issue but providing no explanation for the disruption.
Affected customers received messages apologizing for the inconvenience and encouraging the use of Wi-Fi calling until service is restored.
Outages have also been reported at Cricket Wireless, T-Mobile and Verizon.
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