 Many incumbent operators are facing a reduced number of fixed line subscribers as customers give up second lines or migrate completely to mobile networks. As a result of this process and competition from mobile services which have a much higher penetration than fixed networks, the incumbents are losing voice revenues. This revenue loss is augmented by developments in VoIP markets. Profitable fixed line voice margins are thus tending to reduce under the pressures of mobile infrastructure competition, the challenge of VoIP and regulation to open up the local loop, SO that unbundling can take place, with service providers competing in the local loop. In response, incumbent operators of fixed networks are considering "converged" architectures for "co-opetition" with mobile and VoIP. An example is BT's 21st Century Network (21CN) architecture designed to provide both mobile connection and fixed line to and within the home ("bluephone") and office. It employs a trunk network designed to be the interconnect and backhaul transport for mobile traffic for other carriers on a wholesale basis. Thus fixed-to-mobile "convergence" is changing the fixed infrastructure architecture for all large fixed line operators. INFRASTRUCTURE TO 2030: TELECOM, LAND TRANSPORT, WATER AND ELECTRICITY - ISBN 92-64-02398-4 © OECD 2006 2. TELECOMS INFRASTRUCTURE TO 2030 Mobile telephony and data, including alternative wireless technologies Mobile is now the most important growth sector in telecommunications. It represents over half of new global telecommunications expenditure on infrastructure today and its users have overtaken fixed line users in total numbers from 2001 onwards, as shown below. Nearly all mobile and wireless networks are now digital although there is still a small but rapidly decreasing share of analogue services in Mexico and the United States. Nearly a third of the world's population owned a mobile phone by end-2005; only 23% owned a fixed line. 8 What the fixed network achieved in 130 years was matched by mobile in about ten