e value chain for the telecommunications operator is marked by leveraging capital invested in the network infrastructure to provide services to the subscriber base, traditionally at regulated tariffs, on down to sales and support of customer premises equipment. With the arrival in most countries of some form of market competition, tariffs have (to variable extents) been free to be set by the market, as bulk resellers and other competitors enter and regulatory protection shrinks. Effectively, the traditional value chain has been as shown as below. Figure 2.22. Traditional telecommunications operator value chain - a generic model Corporate operations and services Customer Network support Customer Network infrastructure premises operations Build/maintain services equipment (billing, etc.) In this model, the key to revenue generation is the number of call minutes and keeping them as high as possible while maintaining tariffs. The key to margins, once the capital invested in the network is being written off at a sustainable rate compatible with revenues, is in other parts of the cost base, notably personnel, and the number of staff per 1 000 lines is a key performance indicator. Mobile cellular radio operators The differences in business model for mobile cellular operators are not that significant at a business process level but premises equipment becomes handsets, and the local loop is the radio access network. The major cost of entry is the mobile infrastructure, which includes the cost, not just of a core network behind the radio access network, but also the acquisition and/or rent of suitable sites for cellular basestations. As might be expected, infrastructure costs demand enormous start-up capex. But historically, 2G mobile tends to have much faster payback than fixed line networks as the customer base has built up far more quickly. This is due to the enhanced accessibility, provided suitable pricing and payment plans are in place (especially the pre-paid card in lower disposable income countries, such as Portug