Wednesday, 21 July 2010

Should mobile operators be free to modify content they deliver?

My recent problems with delivering a web service to customers of the O2 network in the UK has got me thinking a lot about what we expect from mobile network providers.

I was trying to think of an analogy with something we are more used to and realised that web content delivery is very much like parcel delivery: we ask for something to be sent to us, they put it in a parcel and a delivery company are responsible for delivering it to us as quickly as possible without damaging it on route. In the internet context, we ask for a web page and we rely on the internet to deliver the page to us without modification.

However, it appears that we have fairly silently allowed the mobile networks to change this arrangement. For some time now we have been, wittingly or unwittingly, allowing many of the mobile networks (O2, T-Mobile, Virgin, Vodafone to name a few in the UK) to reduce the quality of images that we download. This seems fairly harmless and well intended. If it enables us to surf the internet quicker on our mobile phones when we can't see the images well anyway, then surely this is a good thing?

But it's not as simple as that.

What if I want to send someone an image over a mobile network and the image quality really matters. Firstly, I probably won't realise that O2 are going to modify it on route and may discover too late that the lower quality image has gone to print. Secondly, even if I do realise, how do I make sure that the important image isn't compressed? There is no option to bypass this. There is no way of getting hold of the content we have requested. O2 have substituted what we asked for with something inferior and they do it on purpose without asking us or giving us a choice to opt out.

It really calls into question the whole industry of web services. If you pay a web provider for some data and your mobile operator substitutes something different as it passes through their network, who has failed to deliver? If you pay for Flickr's Pro service and use it on your iPad, can you complain to them if the images you view are substandard? Will Flickr have any idea that the images they are sending you are not the ones you get?

And it's not just about images and image quality.

O2 may be going further than other providers, I really don't know. But I do know that they are modifying the very source code of the web pages you access over the internet. So the web services that painstakingly produced and tested by companies around the world are being modified by O2 in such a way that they may not work when they reach your mobile device or 3G connected laptop. You might blame your mobile phone or iPad whilst totally unaware that the problem is actually because O2 have changed the content enough to break it.

Can web content providers test all their services through every mobile network in the world to make sure that you get the service you have paid for? Of course not!

Should you, as a customer, have to figure out whether the problems you are having come from your mobile provider or the original content provider? Of course not!

Mobile phone networks should be reliable and they should provide the content you ask for without modification. If they want to optimise their networks then they can give you the option of accepting a modified network, but it should always be possible to turn off the modifications quickly and easily if anything goes wrong.

The craziest thing about this story is that, as far as I can work it out, O2's optimisations are probably increasing the load on their network and increasing the latency of their network. I have a suspicion that if they turned it all off they would save themselves some money overnight!

I have engineered a partial workaround for the web site I host and it now works on the O2 network and works quicker than it did before!


Travis said...

Related: if I type in a non-existent URL, my (US-based) ISP will grab it and do a search on their branded search page. Effectively hijacking my request.

I suppose the clear solution, and the one we'll likely end up with, is to offer https connections on all requests. I saw this proposed about 6 or 7 years ago, but the problem was the impact on CPU performance. Now I think CPU performance, at least on the webserver edge, isn't as important. So we should start seeing more and more https connections for things not privacy sensitive.

Anonymous said...


You say "I have engineered a partial workaround for the web site I host and it now works on the O2 network and works quicker than it did before!"... could you please tell us (roughly) what you did?



Stuart Roebuck said...


I posted the code on StackOverflow.

Also, note O2's official workaround in my last post The official way to bypass data modification on O2 mobile networks

Hope that helps.

Anonymous said...


https is no solution. At this point, it is a trivial matter for an ISP to run a man-in-the-middle attack and hijack the content anyway. The ISPs are in a position to have perfectly legitimate SSL certificates, and most people would never notice that the certificate presented to them by Gmail is actually owned by their ISP.

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