text: We also use significant judgment in the following areas: 
  (cid:129) determining cash generating units and the allocation of goodwill for  (cid:129) deciding to designate our spectrum licences as assets with indefinite 
  lives since we believe they are likely to be renewed for the 
  useful 
  foreseeable future (see*Goodwill and Intangible assets*, below)  the purpose of impairment testing (see note 13) 
  (cid:129) choosing methods 
  
  for depreciating our property, plant, and 
  equipment 
  the 
  consumption of benefits derived from those assets and are more 
  representative of 
  the 
  the economic substance of 
  underlying assets (see*Property, Plant and Equipment*, below) 
  
  (cid:129) interpreting tax rules and regulations when we calculate income 
  that we believe most  accurately  represent  taxes (see note 27), and 
  (cid:129) determining the probability of loss when we assess contingent 
  the use of  liabilities (see note 27). 