Skip to navigation
Latest News

Customers fume as BT introduces IP sharing

BT engineer

By Nicole Kobie

Posted on 3 May 2013 at 16:20

BT is testing a system that would see broadband customers share IP addresses to avoid the looming IPv4 shortage.

The current IPv4 system is running out of space, and many ISPs and users aren't yet ready to switch to its successor, IPv6.

As a solution, BT is testing a technology called Carrier Grade NAT (CGNAT), which has already been trialed by Plusnet, an ISP owned by BT.

BT said its CGNAT trial would see a single IP address shared between up to 10 customers. "This is the same as the standard practice for mobile broadband connections, using smartphones and tablets today," BT added.

However, CGNAT means you can't set up port forwarding on your router, causing problems for anyone hosting a website or online game. The trial will be tested with customers on BT's "Option 1 Total Broadband" - it's lowest tier, "who on average use the internet the least", the company said.

We do not think these customers will notice any difference at all in their broadband performance

"We believe they are the least likely group of customers to experience any issues or disruptions due to CGNAT, which can interfere with complex online activities like hosting servers at home," BT said. "We do not think these customers will notice any difference at all in their broadband performance, but if any of these customers did have any resulting issues, we would be happy to restore their connection to an individual IP address."

However, it appears users are already noticing problems. "It's causing me a real headache, for a start none of my home servers are now accessible via the web, remote access to my PC is also blocked, and XBox Live requires NAT to be open to work correctly so has reduced multiplayer ability," said one user on the BT forums. "If BT has decided to roll out this solution I really hope that it realises the issues it'll cause its customers."

BT didn't say how many users would be affected or how long the CGNAT trial would run.

BT stressed that it's working to move to IPv6 this year, but said customers will need both IPv4 and IPv6 addresses "for the forseeable future".

(Thanks to PC Pro reader Richard Samson for the tip-off)

Subscribe to PC Pro magazine. We'll give you 3 issues for £1 plus a free gift - click here
User comments

I hope they don't spread this to infinity 2, I use a VPN (among other things e.g. XBL) to connect to my home network so this will be a problem.

I am however IPV6 ready.

Does anyone know if this affects PSN? My brother has a low tier BT package and uses PSN allot.

By tech3475 on 3 May 2013

Wont this cause problems for those trying to track down those pesky kids who download illegally. And what if I share an ip with one of them!

By billy_love on 3 May 2013


Why don't they just give new customers IPv6?

That' what the German equivalent of BT is doing. Customers also don't get a telephone line now, they get VOIP only, unless they pay extra.

By big_D on 5 May 2013

Usual BT foot dragging


Sounds great, but then BT always like to drag things out, you only have to look at ISDN for that.

Presumably they see this as a cost skimming alternative.

By Gindylow on 9 May 2013

won't invest prpperly

Rub people up the wrong way and they shift top another isp


IPv7 Urgently Needed!

What is urgently needed is IPv7, which should be a development of IPv4 with a wider address range, simple as that.

The fundamental reason that IPv6 has not been rolled out is its needless complexity, and that it introduces a myriad of potential security problems due to its numerous untested and unwanted gimmicks. Because of this, most admins turn it off.

All we actually needed was an increase in address width, instead we were offered an unholy mess. That we said 'no' en masse should not be a surprise.

By Anteaus on 22 Nov 2013


Should cope...

By bet1001 on 5 Dec 2013

Leave a comment

You need to Login or Register to comment.



Latest Blog Posts Subscribe to our RSS Feeds
Latest ReviewsSubscribe to our RSS Feeds
Latest Real World Computing


Sponsored Links

Your email:

Your password:

remember me


Hitwise Top 10 Website 2010

PCPro-Computing in the Real World Printed from

Register to receive our regular email newsletter at

The newsletter contains links to our latest PC news, product reviews, features and how-to guides, plus special offers and competitions.