Carphone Warehouse says that it is “surprised” by the high number of customers buying contract phones via its new transactional mobile site.

Despite only going live last week, the mobil- optimised site now accounts for 20% of all online traffic to Carphone Warehouse (CPW) and converts at roughly half the rate of the desktop site.

While this is in line with conversion rate statistics from Monetate, it is impressive for a new site.

The customer journey before a mobile phone purchase often involves brick-and-mortar stores, and as such CPW’s 800 UK outlets remain its primary sales tool.

However Self said that the level of traffic to the site was higher than envisaged and they expect it to grow significantly throughout 2012.

CPW has had a mobile site since November 2010, but the previous version was primarily a research tool to see how customers would respond to it.

Customers could research products but had to phone a call centre to make a purchase.

CPW director of e-commerce Victoria Self declined to give the specific numbers of transactions, but said that the company was “delighted” with the proportion of customers willing make complex purchases on mobile.

Over time we do expect this to change as we extend our accessories range and people instead make the easier purchases, but for the first week a high proportion of sales have been more complex subscription orders.”

Features on the new HTML5 mobile site, which is powered by Usablenet, include a GPS store finder, expandable menus, new search options, deal finder and full m-commerce capabilities.