Dave wrote on Jul 4
th, 2011 at 9:28pm:
...
How is the figure, quoted elsewhere, of 25% of non-commercial calls being origated from BT lines arrived at?
This is never given (by me) as the share originated from BT lines, that would be much greater, it is the share of non-business calls originated by BT (i.e. subject to BT tariffs).
The term "residential" works fine for a landline installation, but seems a little odd for a call from a mobile phone.
The calculation is a little tricky because Ofcom does not separate the Mobile totals into Business and Residential. It can however be done.
In its latest annual
Communications Market report (August 2010) Ofcom provides, at figure 5.60, a breakdown of Business call volumes between Mobile and Landline -
64.6% / 35.4%. When the next report is published, this figure may have to be updated.
All the figures which follow are for Q4 1010 (Jan 2011 - Mar 2011) as published hereand are expressed in millions of minutes.1.
Multiply the figure for Business Landline Calls (Section 2 Table 13, p13): 8,999 by 64.6/35.4 (see above) to give a volume for Business Mobile Calls = 16,422.
2.
Subtract this from the Total of Mobile Calls (Section 3 Table 2, p19): [6731 + 10,136 + 10,906 =] 27,773, to give a volume of Non-business (residential!) Mobile Calls = 11,351.
3.
Add this to the Total of Residential Landline Calls (Section 2 Table 8, p9): 22,478 to give the total for all Non-business calls =
33,829.
The total of BT Residential Landline Calls (Section 2 Table 8, p9) is 8,969, nearly 40% of the total of landline calls.
As a share of the Total Non-Business Calls, using only the latest figures published by Ofcom, it is
26.5%.
Not all calls are included in the published Ofcom figures - calls from around 10% of mobiles are excluded. One therefore feels content to trim a little off. My more detailed figures make a proportionate allowance for the omitted mobile calls to give a BT share of 24%.
All statistics at this level include a degree of fudging, so I am content with
25% as a rough, but fair, figure.