Intangible assets, consisting mainly of telecommunications licences, software and development costs, are initially stated at acquisition or production cost comprising its purchase price, including import duties and non-refundable purchase taxes, after deducting trade discounts and rebates, any directly attributable costs of preparing the assets for their intended use, and, if applicable, attributable borrowing costs. Identifiable intangible assets acquired in a business combination are recognised separately from goodwill at their acquisition date fair values. An intangible asset is identifiable if it is either separable, i.e. capable of being separated or divided from the acquired entity, or arises from contractual or other legal rights. Fair value of an intangible asset is measured using valuation techniques appropriate in the circumstances. Internally developed trademarks and subscriber bases are not recognised as intangible assets. Telecommunications licences Expenditures regarding telecommunications licences are amortised on a straight-line basis over the reservation period from the date when the network is technically ready and the service can be marketed. Research and development costs Development costs are recognised as an intangible asset if and only if the following can be demonstrated: Development costs not fulfilling the above criteria and research costs are expensed as incurred. The Group’s research and development projects mainly concern: Development costs recognised as an intangible asset are amortised on a straight-line basis over their estimated useful life, generally not exceeding three years. Software Software is amortised on a straight-line basis over the expected useful life, where standard useful life is up to five years unless revised. Useful lives of intangible assets are reviewed annually and are adjusted if current estimated useful lives are different from previous estimates. These changes in accounting estimates are recognised prospectively.