For next generation UK broadband, optical fibre is ultimately the preferred technology, and works extremely well for the provision of services to large businesses in central London. According to Chris Smedley, Chief Executive of Geo, there are considerable hurdles to overcome if it is to be seen as an alternative to BT's local access network in residential areas. His comments come on the back of the announcement made by Ofcom saying it will investigate whether the roll-out of fibre to the door of homes and businesses can be accelerated by using the UK's alternative utility infrastructures, including the sewers.

Geo is well placed to comment on the issue. Having owned the network since 2006, it operates an 80km (and growing) optical fibre network based in Thames Water's London sewer system, as well as providing dedicated fibre networks to broadband suppliers such as Carphone Warehouse and Tiscali based on the long-term lease of optical fibre infrastructure. It is the only sewer-based optical fibre network in London.

However, Smedley says it is unproven whether sewer-based networks will deliver these same advantages in for residential areas. Geo points out that not to mention suburban and rural locations, the sewer systems in outer London and other cities, are a very different proposition as they're much smaller or, in some cases, non-existent.

In helping develop next generation networks in the UK, alongside more traditional road digs, Geo believes that sewer-based networks may have a role to play. It may also help address the other (and more immediate) challenge for improving broadband speeds - the high cost of the so-called "middle mile" for optical fibre services between core networks such as Geo's and BT Openreach's access network.

Geo, in addition to its network in the London sewers, also operates a 2,500km national network around the UK and is building a high-speed optical fibre network in partnership with the Welsh Assembly Government in Wales.