About 70,000 BT business broadband customers have had trouble connecting to the internet on Friday due to a technical fault.
About 70,000 customers were affected
BT has confirmed that a fault at its internet switching site in Bletchley at 1230 GMT disrupted the service.
Dial-up internet users also faced a temporary disruption of service.
About two thirds of those affected are now back online and the company is working to resume full service as soon as possible, it said.
"The type of customers impacted are largely small and some medium-sized companies," a BT spokesman said.
"BT has a goodwill policy to address significant prolonged delays with the service and we will deal with these on a case by case basis," he added.
It is however understood that the goodwill policy applies to disruptions which last over several days.
As of 30 September last year, BT retail had 1.28 million broadband connections, a figure which covers business and residential users.
BT is the UK's main broadband provider.
Just last month, the company said that the number of people on broadband in the UK had now surpassed four million.
Including those connected via cable, almost six million people have a fast, always-on connection.
The boom has been fuelled by fierce competition and falling prices, as well as the greater availability of broadband over the phone line.
Here is a representative selection of comments we received from readers. This comments section has now closed.
Unable to transact any business at all this afternoon. Some 80% of our business involves email and/or the internet in one form or the other. We will now need to work an unplanned Friday evening to catch up the backlog....at some cost, but we must look after our customers.
Guy Rowing, Harrow, UK
I tried to restart my internal network, thinking that was the source of the problem. But in doing this my BT router exploded! BT say they will come to fix it on Tuesday, which means three business days without a broadband connection, which is devastating for a small business.
Paul Temperton, Chalfont St Giles, Buckinghamshire
As usual no apology or compensation from BT.
Mr D Godfrey, London, UK
Back on line 17:22 GMT.
Dave Turner, Bournemouth, UK
I experienced problems connecting and the server seems to have been very slow this afternoon.
David Copeman, Barnet, Herts, UK
All service suddenly no longer there and I had to resort to phoning people who I knew would be sending me important emails today and get things faxed or take notes over the phone instead. It made me realise how dependent my business has become on using internet services and email.
Sue Nelson, London, UK
Our business was without a connection for most of the day. Since we rely on it for stock transfers, pricing information, email etc, it was rather frustrating. It's quite common for this to happen although my domestic broadband connection almost never fails.
Graeme, Dundee, Scotland
My business has now been off line for about five hours and the only information I can get is "we are working on it".
Brian Luty, Leeds, UK
The effect of this fault has severely restricted our on-line business plus our preferred method of communication. BT was largely impossible to contact and once we did, all they are concerned with is whether the equipment we use is BT approved; something completely irrelevant...
Arthur Hitchcock, Alton, UK
Both my wife and I were working at home. I am organising and campaign for a major international development charity and she is a local councillor. Service was lost for a couple of hours on both internet and email.
It happened at an extremely important time as I was preparing for an key meeting with a leading UK politician and was suddenly unable to finish my research and preparation for that meeting.
Service is now thankfully back on and I face a Friday evening of catching up on lost time.
Stuart Singleton-White, Reading, UK
We were affected by the technical fault at BT this afternoon.
However, this is the first problem we have ever had with BT in the 4 years that they have been supplying our Broadband service. It was not a major issue because the connection came back in less than an hour.
Yuri Ilukkumbure, London
Lost service for several hours, disabling our website management and remote working employees
Process Management International, Coventry UK
No I was not affected, however, I am interested to know why you are asking the question. Are you asking the same question about every company that has had a problem today, or is it just BT?
Kevin Hayes, East Brent
I run the infrastructure division for an IT company and the link was out for several hours, cutting off customers across the country and severely hampering our ability to conduct business.
Nik Grove, United Kingdom
I blamed some poor builder in the street for drilling through some cable!! Missed all my advertising deadlines and been unable to do anything else all after noon.
Broadband is fast and cheap, but not always reliable. If you really need 99.999% Internet up-time be prepared to pay for a dedicated lease line.
Jim Sharman, Consett, England
Suffered from the outage, but once I got through to the helpdesk they where very helpful in telling me what was going on and what to do.
Our company is the UK subsidiary of a Finnish Plc and were sending the end of year stat's through the internet when this interruption occurred. All afternoon we also had to resort to order picking and deliveries via manual system, which meant certain clients will miss their shipments...
Stephen Takhar, Hinckley,UK
We pay extra for BT's quality of service. Following this disruption, this is something that we will need to re-examine. We will now be working late to make up for the lost time.
Tim Crossland, Romsey, United Kingdom
Luckily we decided to use an alternative broadband provider. It's worked out much cheaper and twice as fast. When you call customer support there aren't any annoying voice prompts - you just get straight through to someone. And luckily we haven't yet had any kind of connection problem.
Tom, Somerton, UK
Had urgent advertising copy to be reviewed and sent to printers, but could not do it. Now had to put back for a whole week. Very disappointing, but to give them credit, BT broadband has been working for most of the time last year. Heard many stories about other providers and their service, so cannot say how good or bad.
Leo, London, UK
We were an internet cafe until about 1pm this afternoon, we've lost loads of money today. This has happened before, but no compensation has ever been forthcoming.
Sue, Uxbridge, UK