You may find that, when you take it gently apart, your old master socket has a bewildering number of components and terminals. Some customers have approached me, confused, asking for advice. It’s obviously time to write something

Changing your old master socket?  Yes, it may be advisable in order to get the best broadband speeds.  You’ll need to read on to find out why.

Old Isn’t Always Bad. What’s Good?

They are solid, hard to break. They are perfectly acceptable for running phone lines. and, with a filter, broadband (but slowly – see below). However, for advice on replacing them with the very latest type, plus moving existing ones, take a look  at our previous blogs here:-

The All-New (-ish) NTE 5C

Moving Your Master Socket

Alternatives to Moving Your Master Socket

Help! There are 6 pins – which ones do I use? “

2 and 5. That’s it. Occasionally 3 (but only if you don’t want the fastest broadband speeds). “3” is sometimes required to enable a phone on an extension socket to ring. (Just for the record, some old office phone systems use pin 4. Some very odd ones use all six. Don’t let this trouble you…)  However, to recap, for home use, 2 and 5 are just fine. They don’t even have to be a specific way around. Add cables to the other terminals and you could potentially create a huge aerial which would attract interference and slow down your internet connection. For broadband, “less is more”. 

Why were they equipped with 6 pins anyway?”

I can’t find any obvious answer. However, a retired ex-BT chap told me that they were equipped with six pins “to allow for future services” when first introduced in the mid-eighties. Lump this bit of misguided futurology with housing estates on the moon, disposable paper clothes, personal hovercraft for all, and routine school morris dancing with aliens.

What’s the “E” screw terminal for?

E” is for earth, used for party lines and earth calling functions. It sits next to the “A” and “B” screw terminals to which are attached the incoming pair of wires from the Openreach network. Party lines? Don’t worry about this one – very few people know what a party line is anyway in 2020. You have to have been born before at least 1970 to understand this quaint and bizarre arrangement of being able to use your neighbour’s phone line. More on party lines here (if you are bored)

What’s the strange silvery-white drum-shaped thing?

It is a surge protector, a sort of fuse. In theory, it protects the equipment attached to the line in the customer’s premises from the effects of a lightening strike. However, a proper strike melts everything anyway, including this component. This assumes that you can still find the socket under the ash and debris of your incinerated former home.

What’s Bad? Why You Might Need To Change It.

The surge protector slows down ADSL/VDSL. Time to change your socket to one of these if you want top speeds. Full stop.


Good in their time. If you are just running telephone services, then that’s just fine. Your old master socket will last forever, but it’s certainly time to change them due to changing times and the universal clamour for faster broadband.

Can You Change Mine, Please?

If you are in North East England, then we do offer a home repair/upgrade service.  Please get in touch. If you are not local to us, then we do network informally with other similar small and friendly telephone engineering companies across the UK.  We may be able to find someone to help you, but ask a favour:- if this information has been helpful, please leave us a review on Google or Facebook. Thanks.