Audit
The results
of the surveys have been audited externally. Each operator’s
figures are statistically valid at the national level to approximately
+ or – 0.5% at a 95% confidence interval. As recommended
by the auditor, the results have been rounded to one decimal
place.
Calls
made
Calls were
made to and from mobiles connected to the automatic call generating
equipment and dedicated fixed test lines: mobile to fixed telephone
line and fixed telephone line to mobile, in the ratio of 2:1.
Calls were
regarded as successful if held for two minutes.
The figures
quoted only reflect the service experienced on the specified
routes, at the time of day that the calls were made and the
type of handset used.
Technical
details
Mobile network
operators use different test equipment and different signal
frequencies and so adjustments have been made to try to compensate
for these differences.
Neither
BT Cellnet and Vodafone’s analogue network were tested
as part of this survey. BT Cellnet and Vodafone’s dual
band capability was tested as part of the survey. For further
information about dual band networks please contact BT Cellnet
or Vodafone at the addresses shown below.
National
and Regional Data
The results
for all mobile phone networks are presented on a national and
regional basis. The UK has been divided into nine areas: London,
South East England, South West England, East Anglia, Midlands,
Northern England, Wales, Scotland, and Northern Ireland(1).
Future
developments
The operators
together with OFTEL and consumer groups are currently working
to further improve the methodology, comparability and accuracy
of the survey approach used.
The results
of subsequent surveys are due to be published every six months.
Further
information
Consumers
wanting further information about the survey should contact
the mobile phone network operators directly.
Legal
Issues
As indicated
above, although the results have been independently audited,
the survey was carried out by the four mobile network operators
according to their own agreed criteria. Therefore OFTEL accepts
no liability in respect of any of the results.
(1)
One2One did not survey Northern Ireland due to having no commercially
available network within the region during the time of the survey.
Orange did not survey Northern Ireland due to technical
reasons.
