Definitions of IMSI, PLMN selector, HPLMN search period,
CBMI and any items of interest.
which is also known as International Mobile Subscriber Identity (IMSI), is a 15-digit
unique identification number which is used to identify a mobile subscriber.
IMSI is associated with all Global System for Mobile Communications (GSM) and
Universal Mobile Telecommunications System (UMTS) networks. IMSI is consist of
three parts, the first three digits indicate the mobile country code (MCC), followed
by either two or three digits which indicate the mobile network code (MNC) and the
remaining digits indicate the mobile subscription identification number (MSIN).
The table below shows the example of the composition of the ISMI mentioned in
Country – Namibia
Operator – MTC
Unique ID – 1930358948
which is also known as Public Land Mobile Network, is any mobile wireless
communication system that use
land-based radio frequency transmitters or base stations as a medium for
transmission of cellular signal and data. PLMN selector can be identified by
the three-digit MCC and followed by the two-digit MNC, which is part of the
ISMI. PLMN can be standalone but often connected to a Public Switched Telephone
Network (PSTN) for telephone communications or with Internet Service Providers (ISP)
for data and internet access. For example, a mobile phone user can be a PLMN
end user. In general, User Equipment (UE) will automatically attempt to access
the PLMN by default. However, the UE will not automatically access forbidden PLMNs
which is also known as Home Public Land Mobile Network, contains the Home
Location Register (HLR) which stores information about each subscriber of this
PLMN. Users roaming from one network to the other network will also receive
subscription information from the HPLMN. HPLMN search period, which currently known
as High Priority PLMN Search Period, defines the interval of time between the
searches for high priority cell by the User Equipment.
which is also known as Cell Broadcast Message Identifier, can be found in the
cell broadcast message header and is used to define the content of the cell
Key Kc: 16 3A 5E CA 28 F0 7C 00
Key Kc is a 64-bit ciphering key which is used for encryption and decryption of
data that being transmitted on the over the wireless communication network. Kc
is used by the GSM network to provide data confidentiality and also
authentication. Ciphering Key Sequence Number (CKSN) is used in the key (Kc)
management in the GSM communication network.
Control Channels (BCCH)
Control Channels (BCCH) is a logical broadcast channel used to identify the
network in a GSM network. This information is used by a mobile station to get
access to the network.
Mobile Subscriber Identity (TMSI)
Mobile Subscriber Identity (TMSI), is a temporary identification number that is
used instead of ISMI to protect the privacy of a mobile subscriber. TMSI is
associated to GSM network and TMSI protects the identity of the mobile
subscriber by intercepting the tracing of the traffic on the radio link.