CityFibre Holdings, which specialises in the rollout of ultrafast fibre optic broadband ( FTTH , FTTP etc. ) infrastructure, has used a spot of basic science to remind people of why existing copper based DSL broadband services might not be the best choice for future investment.

It's widely known that DSL (up to 24Mbps ADSL2+ etc.) solutions are notoriously unreliable and frequently deliver performance that is significantly less than advertised; often through no fault of the ISP. One of the biggest reasons for this, as we've said many times before, is to do with copper line length.


None of this is new and many of our readers will already be aware that ADSL and ADSL2+ services hit problems on lines longer than 6.5km (extremely slow or generally unreliable). Rural areas will naturally experience this more than urban ones as people in such locations usually reside further away from their local telephone exchange.

Crucially CityFibre's comments come at a time when both BT and the UK government are attempting to plough new money into existing copper based infrastructure, which Fairbrother believes should carry the tag of "caveat emptor" (i.e. let the buyer beware).


Fairbrother goes on to note that "high speed VDSL2 doesn’t go as far as low speed ADSL", which marks a stealthy criticism of BT's Fibre-to-the-Cabinet ( FTTC ) based 'up to' 40Mbps superfast broadband services. Contrary to some advertisements, FTTC only uses fibre optic cable so far as your local street cabinet and VDSL2 then delivers the "last mile" connection over an existing copper line to your home.

It goes without saying that CityFibre has a vested interest in plugging the almost unquestionable merits of fibre optic lines versus copper based ones and he's not wrong to do so. The comments are also accompanied by a rather blurry graph (here).

Naturally BT might disagree with CityFibre and could point to the lower costs of deployment (they already have a vast copper network in the ground) for FTTC and the fact that its top speeds will rise to 80Mbps next year and 100Mbps after that. Others might well argue that this simply isn't future proof and more investment could be needed to 'fix' it later on.

The graph used by CityFibre also lists VDSL2 reach but it's unclear whether or not this has been measured from the telephone exchange (most likely) or street cabinet (as used in FTTC). Cabinets reside closer to homes and thus the actual reach would be further than if measured from your exchange.

According to Alcatel-Lucent, a global telecommunications firm, FTTC technology should theoretically be able to deliver speeds of 20Mbps at a distance of about 1000m and 40Mbps at 400m (from the cabinet). A future enhancement called Vectoring, which helps to cut out some of the interference (cross talk), will also be able to deliver speeds of 100Mbps at 400m (details). It remains to be seen if this holds up in the real world.