No general changes of useful lives were effected in 2007. For a discussion on impairment testing, see Note 15 "Goodwill and Other Intangible Assets." The following amortization and depreciation rates were applied.
Trade namesIndividual evaluation, minimum 10%
Licenses for mobile and fixed communicationsLicense period, minimum 5%
Customer relationshipsIndividual evaluation, based on historic and projected churn
Other intangible assets20-33% or individual evaluation
Buildings2-10%
Land improvements2%
Expenditure on improvements to property not owned by the GroupRemaining term of corresponding lease
Mobile networks (base stations and other installations)14.5%
Fixed networks
- Switching systems and transmission systems10-33%
- Transmission media (cable)5-10%
- Equipment for special networks20-33%
- Usufruct agreements of limited durationAgreement period or time corresponding to the underlying tangible fixed asset
- Other installations2-33%
Equipment, tools and installations10-33%
Equipment placed with customers under service arrangementsAgreement term, annuity basis




Amortization, depreciation and impairment losses on intangible assets and property, plant and equipment were distributed by function as follows.


January-December
SEK in millions, except proportions

20072006
Cost of sales

9,6609,203
Selling and marketing expenses

1,4001,149
Administrative expenses

495519
Research and development expenses

149302
Other operating expenses

17130
Total

11,87511,203
Proportion to net sales (%)

12.312.3




Amortization, depreciation and impairment losses are broken down by reportable segment in Note 6 "Segment Information."
Amortization, depreciation and impairment losses were distributed by asset class as follows.


January-December
SEK in millions

20072006
Other intangible assets

2,8372,422
Buildings and land improvements

318375
Mobile networks

3,5993,793
Fixed networks

4,3783,995
Other plant and equipment

743618
Total

11,87511,203