How do I diagnose a fault?
There are several tests to run that will help you diagnose a fault and we request that you do this before contacting BT Wholesale. Start with CP and end user checks to ensure there are no faults with the equipment or problems with the way the service is set up.
If this doesn't reveal the cause of the issue, you'll need to run a Knowledge-Based Diagnostics (KBD) test. The KBD test can affect your end user's service, so make sure you let them know when you're running it.
After you complete CP and end user checks and have run a full KBD test, follow the recommendations accordingly.
To learn more about the KBD and other diagnostic tools, take a look at our online guide https://www.btwholesale.com/pages/static/help-and-support/broadband/knowledge-based-diagnostics.htm.
How do I interpret the KBD outcome?
A KBD test will usually reveal the cause of the problem and give a recommendation on what to do next.
See the KBD Best Practice guides https://www.btwholesale.com/pages/static/help-and-support/broadband/knowledge-based-diagnostics.htm to learn more about KBD outcomes.
KBD has returned a ‘No Fault Found’ result. What do I do?
A 'No Fault Found' test result is returned if the diagnostic tests fail to identify a fault within the BT network.
After completing all CP, End User and KBD tests follow the KBD outcome recommendation.
Refer to the KBD Best Practice for more guidance https://www.btwholesale.com/pages/static/help-and-support/broadband/knowledge-based-diagnostics.htm
What is a MFL code?
During a KBD test, checks that may be carried out include a Copper Line test and/or SFBB Access tests. These tests check the 'Local Access Network' - the connection between the end user's premises and their local exchange.
An Main Fault Location (MFL) code identifies faults found on the end user’s line and indicates the location of the fault. You’ll usually receive an MFL code as the result of a KBD check if there is a line fault.
Some MFL codes require an engineer visit to the location. In some cases you may need to speak with the end user to make an appointment.
The following is a list of MFL codes, the fault location and whether the engineering task requires an appointment with the end user:
OK - No fault was found when the test was performed.
CA - Customer Apparatus. This usually indicates a fault with the end user's set-up or between the main telephone socket (NTE) and the distribution point (DP). An appointment may be made for an engineer to visit the end user's premises and investigate.
LN - Line Fault. A fault was found between the Distribution Point (usually the first telephone pole) and the exchange. An engineer will investigate the issue between the DP and the exchange.
CE - Customer Equipment. A fault has been found indicating that there might be an issue with the customer's equipment. An appointment will be made for an engineer to check the line from the end user's premises back to the serving exchange.
EX - Exchange. A fault has been found within the serving exchange. An engineer will investigate the issue at the exchange.
FU - Frames Unit. A fault has been found on the Main Distribution Frame (MDF) within the serving exchange. An engineer will investigate the issue on the frame.
DT - Diagnostic Test. Diagnostic Test failed to run or returned an inconclusive result.
CO - Cabinet Optical. An issue has been found in the serving cabinet (also known as the Primary Connection Point, or PCP). An engineer will visit the PCP to resolve.
How do I stabilise a circuit?
First, check all CP (Communication Provider) and End User checks confirm there aren’t any local environment setup or wiring issues potentially affecting the service.
A CP user can stabilise a circuit using the DLM Setting tool available from the My Apps section of My BT Wholesale
You’ll find more help with this in our Self Service Repair and Self Service Repair Aide Memoire user guides which you’ll find on our Broadband Faults and Diagnostics page.