BT has finally moved to fix capacity problems at the CLEY telephone exchange (East Norfolk) after residents and an ISP ( AAISP ) complained that the operator had only provided a dismally small amount of broadband bandwidth to the area (a single 10Mbps link), which has to be shared between roughly 400 customers (many of those use 'up to' 8Mbps ADSL (20CN) connections).

Broadband is of course a shared "Best Efforts" service where a little often goes a long way. Indeed ADSL lines, due to various technical issues, rarely deliver even close to the top speed and that allows the bandwidth to be stretched a bit further.

However, according to Andrews & Arnold ( AAISP ), most of their customers in CLEY "can get 7.15Mbps each on their links" and it doesn't take a genius to work out that this level of contention could easily result in a capacity crunch. That's exactly what residents have been complaining about.


At the time BT claimed that CLEY was only at 25% of its capacity, which didn't appear to reflect what locals were experiencing. The issue isn't isolated to one exchange and other areas are known to have similar problems, although ISPs rarely discuss it because of related Non-Disclosure Agreements (NDA) and or a lack of customers on 20CN.

The good news is that, despite BT initially claiming that the exchange did not need an upgrade as it was only at 25% of its capacity, work has now been undertaken to resolve the problem.


Initial reports suggest that the situation around CLEY is now "a lot better", although AAISP would still like to know more about BT's threshold for upgrades and over what period the operator measures a capacity problem before action is taken.

Meanwhile BT informs us that they are "well aware" of rising bandwidth demands and have pledged to invest "tens of millions of pounds this financial year" into the legacy 20CN broadband network, which mostly serves remote and rural areas.

It's worth pointing out that BT's latest 21CN (up to 24Mbps ADSL2+ compatible) network will be able to reach 90% of UK premises during Spring 2013, although that still leaves 10% stuck on 20CN. BT told us that they are also "exploring opportunities to deliver faster speeds" to the final 10%.