Are you receiving a substandard ULL ADSL2+ connection from your ISP?

By Steve Biddle, in , posted: 20-Nov-2011 17:29

One of the most significant changes to the New Zealand telecommunications sector in recent years was the unbundling of the local loop (ULL) in 2007. ULL allowed carriers other than Telecom to install their own equipment in Telecom exchanges or roadside cabinets, and lease the copper cable that runs to your premises to deliver their products and services. In the real world it has meant that carriers have been able to offer xDSL and phone services to end customers without needing to use any of Telecom's hardware.

Around the same time that ULL legislation was introduced, Telecom also agreed to a Government mandated plan to deliver improved broadband speeds to homes and businesses. The cornerstone of this plan was the deployment of a Fibre To The Node (FTTN) network by Chorus, who planned to install around 3500 fibre optic cable fed roadside cabinets nationwide as part of a project known as "cabinetisation". Delivering minimum connection speed of 10Mbps to 80% of New Zealand households and businesses, these cabinets have fibre optic cable linking back into the Telecom network, and contain an Alcatel Lucent 7302 ISAM to provide xDSL services. The architecture of these cabinets is relatively straight forward - the existing copper feeder cable that runs from the Telecom exchange is terminated in the new cabinet on a new Master Distribution Frame (MDF), and existing cabling that runs to local homes and businesses is also terminated on another MDF inside the cabinet. Each line is then connected to the xDSL linecard in the ISAM in the cabinet, meaning that at the press of a few keys xDSL service can be enabled or disabled on a customer's line. Voice services are still provided by Telecom's NEAX switch located in the nearby exchange, and are carried over the copper feeder cable that connects the exchange and cabinet. In some cases where it's been deemed that the copper feeder cable is at, or is approaching the end of it's serviceable life, VMUX hardware is fitted to carry voice calls over IP using the fibre backhaul to the exchange, rather than over the copper cable.

The installation of these cabinets means that the distance of the local loop (the copper cable that runs between the exchange and the premises) was reduced significantly, with close to 50% of premises being less than 500m from a cabinet, and 80% within 1km of a cabinet. Because xDSL performance is dependent on the distance the end user is from the equipment, the shorter the local loop, the better xDSL performance will be. By the end of 2011 when the cabinetisation project is complete, around 80% of the premises in NZ should have an average theoretical DSL sync speed of around 12Mbps to 14Mbps. Homes within 500m of a cabinet or exchange should be seeing ADSL2+ internet speeds of around 15Mbps. 

As part of the industry consultation process before the rollout of the cabinetisation project, Chorus warned of the impact the cabinetisation project would have on ULL providers due to an issue known as midpoint injection - an issue which is now causing significant impact to many consumers who eagerly signed up to  ULL internet plans over the past couple of years.

DSL signals use frequency bands of the radio spectrum that aren't used by voice, allowing voice calls to coexist on the same copper pair with ADSL/ADSL2+ and VDSL signals. Because copper cables used in the network infrastructure typically carry many pairs bundled together, it's possible for signals from nearby pairs to cause interference with each other, something known as crosstalk. Because the ADSL signals transmitted from the new ISAM in the cabinet are a lot stronger than the signals that's have had to travel from the ULL gear in the exchange, the DSL signal from the exchange is in in effect drowned out, resulting in a significant degradation of the xDSL signal, and ultimately slower internet speeds from the ULL connection. Even if the crosstalk had minimal impact, the distance the xDSL signal has had to travel from the exchange means it will always deliver slower speeds than a xDSL signal from the cabinet.

When carriers such as Orcon, Slingshot and Vodafone started installing their own equipment in Telecom exchanges across Auckland they received plenty of media attention and were keen to tell anybody who was keen to listen how great this move was. Competition had come they exclaimed, promising in some cases to offer better, cheaper broadband and phone services to end users. What is unclear is whether these providers clearly understood the implications of the cabinetisation project, and more importantly the effects of midpoint injection that Chorus had warned of in their industry briefings. Move forward to now, and their eagerness to sign up customers is arguably resulting in many of their customers receiving a substandard service, with many being unaware of the problem, or the solution.

In the last couple of months Chorus have been busy completing the last stages of their cabinetisation project, which has included the installation of several hundred new cabinets in the Auckland region. Many of these new cabinets are connected to exchanges serving customers that are currently on ULL connections, and the immediate result for most of these customers is a line with increased attenuation, which will result in a degraded DSL service with slower speeds. The solution to the problem is straight forward, the ISP simply needs to migrate these users from their own ULL gear in the exchange and connect them to the Chorus ISAM in the cabinet using a Telecom Wholesale UBA connection. In the real world however, the business case for such a move isn't quite so simple. Because DSL services offered by Telecom Wholesale are a regulated product with pricing set by the Commerce Commission, the net cost to the ISP increases significantly as the cost of these wholesale connections is significantly more than the cost of delivering a ULL connection. Because some ISP's used a marketing ploy of cheaper pricing for customers using their ULL network compared to those customers who were connected to Telecom Wholesale connections, many end users may be faced with a price increase for their internet and phone services if they are to move from a ULL connection back to Telecom Wholesale.

How do I tell if I could be affected? 

The simplest way to establish the quality of your DSL connection is to look at the Chorus website - and enter your address. You will instantly see whether you're served from an exchange or cabinet, and whether your home is covered by ADSL+ and/or VDSL2 services. The next step is to log into your  modem and look at your connection stats. Providing exact details of how to do this is beyond the scope of this post, but in most modems these details should be fairly easy to access. What you are looking for are stats like the following:


If you are within the footprint of a cabinet you should realistically be seeing a DSL sync rate in your modem of at least 10000kbps, with a good connection showing stats of up to 18000kbps. If you are on a Telecom Wholesale connection you should see a noise margin of around 12dB reported by your modem. If you are on a ULL connection you will potentially see a noise margin of around 6dB, as providers such as Orcon have chosen to use a more aggressive noise margin for their xDSL connections. If the Telecom Wholesale map shows you as being serviced from a cabinet, and your modem reports a noise margin of around 6dB you are potentially receiving a substandard connection.

The router screenshot example used above is a friend's Orcon ULL connection taken last month, with an attenuation of 54 dBm which is exceptionally poor. His DSL sync speed was 880000, which meant his internet speeds could be a maximum of 800 kbps per second. Telecom Wholesale provide a provisioning tool that any ISP can access that will show an approximate estimate of the attenuation and sync speeds at any address on their network - his address showed he should be seeing sync speeds of between 15000 kbps and 16000 kbps from the connection to his local cabinet. Within days of requesting a chance Orcon had moved him to a Telecom Wholesale connection and his connection was now around 20x faster than it used to be. There have been a growing number of threads on Geekzone discussing this issue over the past couple of months and all with similar end results, so his story is anything but unique.

The vast majority of ULL gear was installed in exchanges in the Auckland region so there are potentially hundreds, if not thousands, of internet users receiving sub standard speeds from their ISP. The cabinet migration schedule isn't a secret, and some ISP's have actively migrated ULL users across to Telecom Wholesale connections before cabinets have been installed, however others have chosen not to do this. If you know you are on a ULL connection and unhappy with your performance some basic checks such as those above could greatly improve your internet speeds!

Other related posts:
Is the TCF mobile blacklist fuelling New Zealand’s latest crime fad?
Spark Paging network shutdown – the event nobody cares about? Not quite.
UFB voice, power cuts, copper invincibility and mainstream media FUD.

comments powered by Disqus

sbiddle's profile

Steve Biddle
New Zealand

I'm an engineer who loves building solutions to solve problems. I'll also a co-founder of the travel site. 

I also love sharing my views and analysis of the tech world on this blog, along with the odd story about aviation and the travel industry.

My interests and skillset include:

*VoIP (Voice over IP). I work with various brands of hardware and PBX's on a daily basis
  -Asterisk (incl PiaF, FreePBX, Elastix)

  -xDSL deployments

*Structured cabling
  -Home/office cabling
  -Phone & Data

*Computer networking
  -Mikrotik hardware
  -WAN/LAN solutions

*Wireless solutions
  -Motel/Hotel hotspot deployments
  -Outdoor wireless deployments, both small and large scale
  -Temporary wireless deployments
*CCTV solutions
  -Analogue and IP

I'm an #avgeek who loves to travel the world (preferably in seat 1A) and stay in nice hotels.

+My views do no represent my employer. I'm sure they'll be happy to give their own if you ask them.

You can contact me here or by email at