O2 has conceded that it has a problem with its network availability in areas of East London and Essex.
Users in these areas may be having problems making calls or using data at the moment, although O2 says it is working on the problem.
A status update on its website says, "Unexpected issues: We've got a problem that means you can't make calls, use the internet, or send/get emails the east London/Essex area."
More downtime for some
The latest outage follows a previous bout of down time due to theft and vandalism at its East London site in mid-May.
O2 hasn't said that the current service impairment is down to thieves or vandals this time, although some of the same customers will be affected.