Pico GSM cells, what's the fuss all about? | The Register

Pico GSM cells, what's the fuss all about? | The Register: "1781.7-1785MHz paired with 1876.7-1880MHz (known as the GSM Guard bands)1781.7-1785MHz paired with 1876.7-1880MHz (known as the GSM Guard bands)"

The GSM Guard bands were put in place as the seperate the GSM bands from the DECT bands. 20 years ago radio kit tended to bleed into neighbouring areas, so Ofcom reserved these chunks of 3.3MHz to ensure that there would be no interference with DECT.

Nowadays radio kit is much better and doesn't, so Ofcom auctioned off the spectrum and made £3.8m for the government in the process (peanuts compared to the £22bn they made on 3G, but it's some cash to pay for a tank in Iraq or something).

The major advantage is that all GSM phones will "listen" on those frequencies as their normal behaviour, so in theory easy to run a low power GSM network and use off-the-shelf phones. Of course there's more to it than that and the article goes on to explain that.