I had a call from my landline provider last week. After the faux bonhomie of the initial greeting feebly subsided, it was down to business. It was explained to me that they weren't sure that I was getting the best value from my phone package, and they seemed to be rather keen that I alter it. For a fee, obviously. "I'm looking here at the kind of calls you've been making," said the man tasked with convincing me – but at that point, I felt invaded. I'd always hoped that this information would be between me and some faceless, corporate entity. I knew it was this chap's job to scan the calls I'd been making, but ultimately I'd rather the company just billed me and then destroyed the evidence. (Not that I've been doing anything untoward, you understand.)

But they can't do that. In this post-9/11 world of heightened national security, EU-wide rules have been implemented to force telecoms providers to hang on to that data, and each EU country complies with varying degrees of enthusiasm. In the UK, we're governed by the Data Retention (EC Directive) Regulations 2009, which requires information about our calls to be kept for 12 months. The data retained by mobile networks are obviously a lot richer, mainly because customers use the service while moving about. The location data for my landline calls would make a staggeringly uninteresting data set (living room? bedroom?), but any mobile activity you generate is embellished with precise co-ordinates for your longitude and latitude. And it's not just voice calls we're talking about – it's every time your phone automatically checks the network for any new emails, tweets or recent moves made in games of online Scrabble.

Some people aren't too happy about this, and one of them is a German Green Party politician, Malte Spitz. He recently took Deutsche Telekom to court in order to obtain all the information they held about him and, perhaps surprisingly, the court ruled in his favour. In return he was given a weighty 36,000-line spreadsheet containing comprehensive information about his movements over the previous six months. In a stunning piece of data visualisation by the newspaper Die Zeit, that was converted into an interactive map of Spitz moving about the country. You can play, forward and rewind through the data, watching the dot representing him move around Berlin, take the train to Munich and much else. You can also read comments pulled in from his Twitter account from that particular day. It provides a startling, graphic reminder of the level of detail that's generated by the phones we carry around in our pockets.

The fact that a commercial entity holds all this information – albeit under orders from the government – inevitably sets alarm bells ringing. Does this not have the potential to turn into a supermarket loyalty card scenario, but considerably more sinister?

According to Rob Bratby, partner at the business law firm Olswang, we should be reassured by the fact that there are a hefty stack of checks and balances governing how that information can be accessed. "There are privacy regulations that apply to telecoms operators which say that behavioural information can't be used for anything other than billing people," he says. "In theory, data mining could establish, say, the kind of shops you visit, but in practice they're prohibited from doing that."

What a relief. Except, of course, we're happily giving that kind of information voluntarily these days. The number of apps for phones that request information about our location is booming; it would only require a mobile network to create such an app and us to grant permission for them to collect that data – for a second time! – for them to be able to use that data far more creatively. Of course, this is just another stage in the long, slow surrender of information that seems to go hand-in-hand with technological advancement.

About six years ago a range of Xerox printers started including a series of microscopic dots in every printout, linking it for ever to that particular printer, at which point I wouldn't have blamed everyone for junking any technology and living the rest of their lives using Stone Age implements.