Millions of mobile users in the UK are currently not receiving government text message alerts about coronavirus.
The SMS – which tells people to stay home – started shipping on Tuesday morning.
But Vodafone confirmed that it only expects to end the process as soon as Wednesday.
One expert says it highlights the drawbacks of not having a system that can illuminate a message on people’s phones at the same time.
Vodafone is the only four major UK networks that do not complete the work.
The trio told BBC News that they had sent the text to 10.7 million phone numbers on Tuesday afternoon.
EE said it completed the process yesterday, transmitting approximately 1,000 messages per second.
O2 has also confirmed that all its subscribers have been referred for this job.
Vodafone said it was still sending texts in batches of millions per hour, but was required until sometime on Wednesday afternoon to complete the process.
“We have sent most of the messages and we intend to end this process soon,” the spokesman said.
“We paused to send them overnight so we would not disturb people while they were sleeping.”
The factory suspended the process at 20:00GMT to avoid waking up children who own the phone. You need to send a total of approximately 18 million texts.
The full government message read:
GOV.UK CORONAVIRUS ALERT. New rules that apply now: you must stay home. More details and release at Gov.uk/coronavirus Stay at home. Protect the NHS. Save lives.