I have an inconveniently-placed phone jack in my office, so I am running a 10m phone cable from the wall jack to the modem, which is on my desk.

Consequently, I have a very short ethernet cable between the modem and the computer. I know that within reason, the length of the ethernet cable does not make a difference.

My question is: would my connection be significantly faster if I moved the modem and used a short, high-quality phone cable between the modem and the wall?

  • How long do you think the line is from your place to the phone company's central office? I doubt that reducing the total run by a few feet will make any difference. – Jamie Hanrahan Aug 5 '15 at 3:41

My question is: would my connection be significantly faster if I moved the modem and used a short, high-quality phone cable between the modem and the wall?

It's not easy to answer. Yes, probably. Note that your question uses the words "significantly faster". This is what I cannot tell you. This could only be answered after testing because it depends on your phone connection quality and your phone cable quality. But generally speaking you are indeed creating better conditions if you shorten the phone cable.

Phone cables are more sensitive to length than ethernet cat5 cables. So, if you can choose between a lengthier phone cable or a cat5 cable, always choose the cat5. The best solution is to keep your phone cable as short as physically possible. Telephone cables will increase attenuation the lengthier they are.

  • Thanks, what I really wanted to know was which cable was more sensitive to length. – Andrew Swift Jul 20 '11 at 12:55

Considering you have several hundred metres (or maybe several Km) of phone wiring + joints & cabinets between your socket and the local exchange/CO, a few more metres is not generally going to make a significant difference.

That said, some extension leads and reels use very poor quality cable that can really mess up broadband signals due mainly to the characteristics of the cable and not much to do with the extra length. Beyond that, A Dwarf is right - if the choice is between more phone cable or more cat 5, add the network stuff.


I just had very slow ADSL2+ internet speed after moving my modem using a 5m telephone cable. I did what some 'experts' suggested and used 2 different brand new top quality cables, but the speed was at least 5 times slower. I ended up using a 1m telephone cable to the modem and got a longer Ethernet cable and it is now fast again.


This depends greatly on your DSL speed. ADSL and ADSL2+ are very sensitive to distance. While increasing your distance may not affect your speed per say, it can affect the modem's ability to sync properly with the DSLAM and can cause a lower sync rate, line, CV or HEC errors (either causing slower speeds or a bouncing circuit).

Approximate distance limits are:
anything below 1.5/768 - 12,000+ Ft
3.0/768 - 10,000 Ft
6.0/768-1.0 - 8,000 Ft
8.0/768-1.0 - 6,000 Ft
10.0/1.0 - 3,000 Ft
15.0/1.0 - 3,000 Ft

These limits are for dry loops, lineshare will be different (usually slower speeds, longer distances allowed, but not by much). Also, keep in mind that this is actual cable distance, not street distance to the CO - in other words, you may be able to walk to the CO in 3000 Ft or less, but the cable could be traveling 7000 Ft to get there.

Now if you have SDSL or IDSL, you have much longer limits and usually a much stronger signal.

  • 1 foot = 0.3048 meter – kokbira Aug 17 '11 at 20:08

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