IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Organisation Remarks
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S 2.189 Blocking of the mobile phone in the event of
its loss
Initiation responsibility: Head of IT Section, IT Security Management,
users
Implementation responsibility: Users
In the event that either the SIM card or the mobile phone are lost, any costs
incurred as a result of misuse of the mobile phone connection will be borne by
the SIM card holder. Therefore arrangements should be made immediately for
the network provider to block the SIM card in order to exclude the possibility
of the card being misused and the associated financial loss.
In addition, the requirement to enter the SIM card's PIN should always be
enabled (see S 4.114 Use of the security mechanisms provided on mobile
phones). If the card should be stolen or lost, this prevents the SIM card being
used or evaluated by an unauthorised person. However, the user will only be
required to enter the PIN if the mobile phone is switched on. If the mobile
phone is stolen when it is already switched on, a third party could use it to
make calls until the battery is exhausted!
If the mobile phone is lost or stolen, it is also possible for the network
provider to prohibit further use of the mobile phone by placing it on a
"blacklist". To do this, the network provider needs the identifying number of
the phone, the International Mobile Equipment Identifier (IMEI). This is often
found on the back of the phone and should therefore be written down and kept
apart from the device.
Care should be taken to ensure that the IMEI which goes with the mobile
phone is notified in writing at the time of purchase. This number can also be
read from the mobile phone itself, however the procedure involved is not
standard for all mobile phones. The identifying number is often to be found on
the identification plate underneath the battery or it can be displayed by
entering "*#06#".
To ensure that misuse of the SIM card is noticed promptly, the itemised call
breakdown should always be checked for inexplicable charges and destination
numbers.
All the data which is required to block the SIM card or mobile phone should
be at hand but kept separately from the mobile terminal itself. This data is as
follows:
- the call number of the mobile phone connection and the associated SIM
card number,
- the serial number of the mobile phone,
- the service number of the network provider which has to be called in order
to have the phone blocked and
- the service number password and customer number, i.e. the data which is
needed in order to authenticate oneself to the network provider.
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IT-Baseline Protection Manual: Oktober 2000
Get SIM card blocked as
soon as it is lost!