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Glossary
205
PIN (Personal Identification Number)
Security code that protects the phone against
unauthorised use. The PIN is supplied by the
service provider with the SIM card. It may be a four
to eight-digit number and can be changed, as
required.
Proxy Server
A proxy server resides between a Web client, such
as a web browser, and a real Web server and acts
as an intermediary between them. When some
people browse a web site, their browser is not
actually connecting to the web server. The request
from their browser goes to a proxy server, and the
proxy server makes the request to the web server.
A proxy server can improve performance for groups
of users because it cache the results of all requests
for a certain amount of a time. If a user requests a
web page that it already loaded for another user, it
reloads the page instead of forwarding the request
to the Web server, which can be a time-consuming
operation.
PUK (PIN Unblocking Key)
Security code used to unlock the phone when an
incorrect PIN has been entered three times in
succession. The eight-digit number is supplied by
the service provider with the SIM card.
Roaming
Use of your phone when you are outside your home
area (when travelling for example).