Please note that this article is a summary of choices for the more technically minded (and ourselves) and is not a comprehensive "How to".
How to Raise a BT Line Fault at wikiHow.

To check it is not a transient problem caused by something other than your equipment and line.

• Reboot your router! To remove the chance of a stale session, switch off your router for at least 20 minutes.
• BT Service Status page or call 0800 169 0199
  
• BT Fault report and tracking page
• BT Wholesale Broadband Incident Report - courtesy of AAISP*
• Perform a simple BT Line Test and test the connection via the master socket - Dial 17070 for a BT test line - It tells you the phone number for the line and provides quiet line test.
• Check wiring and replace parts where possible*
• List of potential connection problems
• Worse when there is bad weather? Do you have 2 lines?
  

Contacting BT Broadband

BT Broadband Business Internet Services - 0845 600 7020

• Press 1 - For Broadband order enquiries including moving premises
• Press 2 - Existing customer with a technical problem or enquiry
• Press 3 - For Billing Enquiries
• Press 8 - If you are a Residential customer
• Press 9 - To speak to an advisor
• Press 0 - Hear these options
  

Further advice for ongoing problems.

• If you get stuck in First Line support and you believe that they can't help you any further, you can ask to speak to a "Product Specialist" to escalate your call. (BT's own advice to us)
• You can log on using the BT ADSL Test account using the details below (this bypasses your username and password problems, authenticates you on the network with no access to the Internet except for an information page)
  

ADSL Test account details

• Username: bt_test@startup_domain
• Password: <no password please leave blank>
• More info

Finally, our best advice is not to sign up to BT in the first place (or cancel/migrate as soon as your first 12 months are up). Instead, sign up to a smaller reseller (you can use the ISP review top 10 providers), they might be a few pounds a month more expensive, but if you rely on your Internet connection (especially for business purposes), you'll be glad you did. We particularly recommend Andrews & Arnold*

BT Phone numbers

For information purposes only:- provided by saynoto0870.com on 17th May 2008.

* denotes some referal or partnership with these suppliers via the links given. Check out our stance on reviews and recommendations.