Given that there are more mobile phones registered in Germany than there are inhabitants, it is not surprising that mobile phone ticketing is seen as having great potential, in parallel with or as a successor to smart cards. So a number of operators and regional transport associations have been looking at options for mobile phone ticketing over the past few years. Following extensive trials, the mobile phone ticketing project led by Deutsche Bahn is now being expanded to cover more regional transport operators. Offering greater flexibility than smart cards, the Near Field Communication technology will be rolled out across Germany from 2011. Touch&Travel offers the prospect of greater freedom from tariff barriers as users travel around the country. The association of German urban transport providers nation-wide e-ticketing standard, known as the Core Application, has been under development since 2002. It provides a standard for fare calculation and cashless payment, as well as revenue allocation and the back office interoperability that allows journeys to be made with different operators in different cities. Despite the fact that all the existing systems are using the same standard, she adds that 'they are still using different collection methods. Therefore true countrywide interoperability is possible, but not yet fully realised. The association is now trying to rationalise the number of e-ticketing platforms in use across the country, but it is a slow process. Although true interoperability may only be delivered through convergence on a single medium, it is likely that at least two will remain in the longer term, perhaps Touch&Travel as the mobile phone platform plus a conventional smart card.