117
Abbreviations and Acronyms
116
What is roaming?
Roaming allows you to move from one base station (cell)
to another or from one network to another without
affecting the call.
What is digital?
Early mobile phones relied on analogue systems. Analogue
radio systems transmit the voice signal in its original form,
whereas digital technology transforms the microphone
signal into number sequences (digits) and transmits these.
When received, the digital signal is decoded so that you
can hear the sender’s voice. Digital signals do not degrade
in quality as long as the data is received, and they can be
compressed to take up less memory.
What is Dual Band?
A dual band mobile has the capability to automatically
switch between frequencies. It can therefore operate on
two or more frequency bands, e.g. 900 Mhz and 1800 Mhz.
The O
2
X1 is a dual band mobile.
What is a SIM?
Subscriber Identity Module or SIM is the little gold-plated
plastic card that you get from O
2
and which holds the
unique data the network needs to identify your mobile.
What is PIN and what is PUK?
Access to use a mobile is most often protected by a code
known as ‘PIN’ – Personal Identification Number. Your SIM
card comes with a default PIN that you can change to any
code you prefer. See page 81 for details. If you forget your
code, or by mistake enter a faulty code three times in a
row, the SIM card will lock. To unlock, you must enter the
Personal Unblocking Key or ‘PUK’ code which you can get
from O
2
Customer Services.
What is IMEI?
IMEI stands for International Mobile Equipment Identifier
and is an identification system that can recognise every
mobile by a specific number. If a mobile is stolen, the IMEI
system is capable of blocking it on all network operators
that support the system.
