Troubleshooting intermittent faults


Intermittent faults can be frustrating for both the end user and ourselves from a support perspective. Rarely is there a simple “make this line stable again” fix, and some of the changes we can make can have implications to the speed achieved.

Normally there is a logical reason for intermittent connections, and why a stable line rapidly goes down hill. Here is a list of some of the common causes:

• NUMBER 1 CAUSE – Noisy phone line
• NUMBER 2 CAUSE – Faulty router
• NUMBER 3 CAUSE – Faulty filter
• Faulty or damaged phone cable to the router
• Long extension cables
• Operating router from a slave socket, as opposed to the master socket
• Router recently moved next to radiator and overheating
• New electrical cables run next to the phone cables (electrical interference)
• Weather related intermittence (external to premises)
• Sky TV boxes not sitting behind filter
• Other equipment on the same line interfering

Some of the more unusual reasons we have seen include:
• Street light interference
• Farmers electric fence
• Christmas tree lights
• Electrical interference from pylons
• Baby monitors

Given the wide range of possible scenarios the easiest way to diagnose intermittent faults is to logically rule out internal issues before we raise this further. The chances are that with an intermittent fault an engineer appointment will need to be booked. So as long as we can rule out any equipment up to the master phone socket, we can be confident the fault must be external and beyond what  you are expected to be responsible for.

Checks To Complete

1. Has all non-DSL equipment been removed from the line?
This is a good first step to ensure that what you’re dealing with is either the broadband or the phone line, not third party equipment. If this isn’t possible during the day, why not try this over night? You can soon see in the session history logs of the control panel if there is a difference. Disconnect phones, fax machines, and Sky boxes from both the master phone socket and any associated slave sockets.

2. Confirmation that you have replaced the filter, cable and router. BE HONEST.
Stipulate exactly what you have changed so that we are informed and we don’t have to ask.
We know this part is a pain. No one wants to go and buy a new router, but the number of faults that are resolved by replacing hardware is staggering. The £70 you spend on a new router is a fraction of the cost of an engineer visit to tell you that they think your hardware is faulty. The age or manufacturer doesn’t rule out the possibility that it is at fault.

3. Is it connected to the master socket? Is electrical interference possible?
As per some of the examples above, lots of issues have been the result of electrical interference which is sometimes referred to as REIN (Repetitive Electrical Impulse Noise). Simply ensuring that no electrical cables or products are near to the phone socket or cables should be enough.

4. Are there any patterns to the intermittence?
We would like to know if there are time of day related issues. If the evening is worse, is it because the phone is also in use, or is it because the TV is on and the router sits next to it. Both scenarios can effect the quality and reliability of the connection.
Make use of the session history page within the control panel. It shows you the length of sessions and the disconnection cause. Make use of the glossary tab on this page if you are unsure what the disconnection causes mean.

5. How often are the disconnections occurring?
For a carrier take intermittent issues seriously we need to see at least 4 disconnections every hour, if not more frequently. Disconnections occurring every couple of hours, or a couple of times a day, although annoying, are not going to be classed as intermittent. If we end up arranging an engineer visit, and the engineer can’t see this happening, or their diagnostics fail to see a random drop, they will simply walk away stating “right when tested” and the visit becomes chargeable.

6. Testing the phone line
Checking to make sure that the line is clear and free from interference is important. Noise on a phone line for voice issues can cause it to drop intermittently and it can severely reduce the performance of the line. From a handset dial:

17070 and select option 2

When you dial this Openreach test number the phone line will be read back to you. If you press ‘2’ from your keypad you can access the ‘Quiet Line Test’ facility which allows you a chance to carefully listen for any noise and crackles on the line. If these are present then you may like to also run this test with all broadband equipment disconnected.

If it is apparent that the line isn’t as clear as it should be then this should be reported to the phone line provider with emphasis placed on the quality of the voice call as opposed to any broadband issues. Resolving noise issues can help broadband fault conditions dramatically.

7. Diagnostic Tests & Fault Raising
In all honesty diagnostic tests are unlikely to provide you the cause of the intermittence. More often than not they confirm what they see at that moment in time, as opposed to factoring in what is being witnessed over a period of time. However, sometimes they will share with you a potential fault. Please read through the results carefully and use this to raise the fault to our team confirming all the steps you have completed.

Intermittent Broadband Check List

1. I have removed all DSL equipment. Was any difference noticed?

2. What are the makes and models of routers tested on this line? Do they all exhibit the same level of

3. How many filters and phone cables have been tested so far?

4. When I dialled 17070 and selected option 2, I can confirm that the phone line was… (eg nice and
quiet, crackly, silent etc)

5. I can confirm that all tests were carried out from what I believe to be the master phone socket?

6. If the phone socket has a hidden test socket behind a front plate, has this been tried? Did it make
any difference?

7. I have been observing the following patterns to the intermittence (eg every 3-4 minutes, every 3
minutes 20 seconds, every couple of hours, every couple of days, or only during office hours):

8. I have made sure that there is no electrical interference possible. I can confirm no electrical cables
are near the phone socket or cables to the router.

9. The fault started from this time and date (eg we have observed issues since 10/02/2019 14:00)