This is a commonly asked question in court. If it were true, then a cell site located in the centre of London would cover parts of neighbouring counties including Surrey, Kent, Essex, Berkshire and Hertfordshire! The first mobile networks were analogue (Cellnet/Vodafone) and deployed cell sites in this way hoping that they would each cover a city. Once mobile phones started to become popular, networks realised that they would need many more cell sites to cater for the volume of traffic.
With the exponential growth of mobile phone sales and the introduction of digital GSM networks in the 1990’s, network operators got busy building many thousands of cell sites to provide sufficient capacity. Each GSM network operator has at least 10,000 cell sites including micro and pico cells.
We can still experience extensive coverage from cell sites deployed in certain areas. Extremely rural areas or cell sites deployed on the coast can still provide service for many kilometres. In my experience I have encountered cells providing service in this type of area for 20Km. Networks purposely deploy cell sites at ports and channel crossings in order to attract roaming traffic.
This does not mean that data is not available after 12 months!
There are sensitive techniques for live cell site work which records much more data, but this is not available within historic call data records.
Science by its very nature is not precise. The data provided to us is very accurate.
Cell Site Analysis Truths & Myths
Cell Site Analysis Truths &
What is CSA?
• Likely location of mobile phone(s) through
examination of call data records, with or
without radio frequency surveys
• Presented by expert witness, evidence
being both relevant and reliable
• Introduced by Crown or defence in support of their case
• Operators by law have to retain call data
records for a minimum of 12 months
No Calls – No Data
• Operators will in general only retain
records relating to call activity
• GPRS Data is frequently available, giving
data without call activity
• There are several exceptions including
Home Location Register updates
Does your phone use
nearest Cell Site?
• Not always, topography and local building
clutter, may cause a distant site to provide
a better service than the nearest site
• Also variable in the use of GPRS sites
• May vary with the hardware design
Can cell site pinpoint
• Cell Site Analysis cannot pinpoint precise
locations of a mobile phone
• However, depending upon call data
analysis, it may be possible to locate a
mobile to within a few hundred metres
Is CSA an exact science?
• The data we work with is
precise and therefore fact
based and can be relied
upon for accuracy
• It is often used to prove or
disprove an inference and
may be supported by other
evidence i.e. ANPR, CCTV
Does a Bus or Lorry
Driving Past Affect Cell Site Signals?
• This generally does not apply as network
operators employ techniques to avoid
unnecessary handover between cells
• In certain situations
however, if in close
proximity to a stationary
large vehicle, this could
Could it be that the network was busy
at the time of the call and a different cell
site was used because of this?
•This can and does happen but only on
certain networks, in busy areas at busy
Does the weather affect
• Very limited effects due to frequency of
signals and low power cell sites
• Severe weather will affect all local cell
When are Temporary
Cell Sites Used?
• To provide coverage or additional capacity
at a specific event
• A common event for temporary cells is
Glastonbury due to volume of people and
rural setting which is not well covered.
How many SMS (text messages)
are sent across all UK networks
• Over 12.5 BILLION!