Telecoms Acronyms (CAMEL IN)

Question 1

MSC

Answer 1

Mobile Switching Center

Question 2

is the core switching entity in the network. Users of the GSM network are registered
with an MSC; all calls to and from the user are controlled by the MSC. A GSM network has
one or more MSCs, geographically distributed.

Answer 2

MSC - Mobile Switching Center

Question 3

VLR

Answer 3

Visitor Location Register

Question 4

contains subscriber data for subscribers registered in an MSC. Every MSC contains a ___. Although MSC and ___ are individually addressable, they are always contained in one integrated node.

Answer 4

(VLR) Visitor Location Register

Question 5

GMSC

Answer 5

Gateway MSC

Question 6

is the switching entity that controls mobile terminating calls. When a call is established towards a GSM subscriber, a ___ contacts the HLR of that subscriber, to obtain the address of the MSC where that subscriber is currently registered. That MSC address is used to route the call to that subscriber

Answer 6

(GMSC) Gateway MSC

Question 7

HLR

Answer 7

Home Location Register

Question 8

is the database that contains a subscription record for each subscriber of the network. A GSM subscriber is normally associated with one particular ____. The ____ is responsible for the sending of subscription data to the VLR (during registration) or GMSC (during mobile terminating call handling).

Answer 8

(HLR) Home Location Register

Question 9

CN

Answer 9

Core Network

Question 10

consists of, amongst other things, MSC(s), GMSC(s) and HLR(s). These entities are the main components for call handling and subscriber management. Other main entities in the ___ are the equipment identification register (EIR) and authentication centre
(AUC). CAMEL has no interaction with the EIR and AUC; hence EIR and AUC are not further
discussed.

Answer 10

(CN) Core Network

Question 11

BSS

Answer 11

Base Station System

Question 12

is composed of one or more base station controllers (BSC) and one or more base transceiver stations (BTS). The BTS contains one or more transceivers (TRX). The TRX is responsible for radio signal transmission and reception. BTS and BSC are connected through the Abis interface. The ___ is connected to the MSC through the A interface.

Answer 12

(BSS) Base Station System

Question 13

MS

Answer 13

Mobile Station

Question 14

is the GSM handset.

Answer 14

(MS) Mobile Station

Question 15

PLMN

Answer 15

Public Land Mobile Network

Question 16

TDMA

Answer 16

Time Division Multiple Access

Question 17

CDMA

Answer 17

Code Division Multiple Access

Question 18

HPLMN

Answer 18

Home PLMN

Question 19

the ___ is the GSM network that a GSM user is a subscriber of. That implies that GSM user’s subscription data resides in the HLR in that PLMN. The HLR may transfer the subscription data to a VLR (during registration in a PLMN) or a GMSC (during mobile terminating call handling). The HPLMN may also contain various service nodes, such as
a short message service centre (SMSC), service control point (SCP), etc.

Answer 19

(HPLMN) Home PLMN

Question 20

VPLMN

Answer 20

Visited PLMN

Question 21

the ____ is the GSM network where a subscriber is currently registered. The subscriber may be registered in her HPLMN or in another PLMN. In the latter case, the subscriber is outbound roaming (from HPLMN’s perspective) and inbound roaming
(from ___ ’s perspective). When the subscriber is currently registered in her HPLMN, then the HPLMN is at the same time ___.

Answer 21

(VPLMN) Visited PLMN

Question 22

IPLMN

Answer 22

Interrogating PLMN

Question 23

the ___is the PLMN containing the GMSC that handles mobile terminating (MT) calls. MT calls are always handled by a GMSC in the PLMN, regardless of the origin of the call. For most operators, MT call handling is done by a GMSC in the HPLMN; in that case, the HPLMN is at the same time ___. This implies that calls destined for a GSM
subscriber are always routed to the HPLMN of that GSM subscriber. Once the call has arrived in the HPLMN, the HPLMN acts as ___. MT call handling will be described in more detail in subsequent sections. When basic optimal routing (BOR) is applied, the ___is not the same PLMN as the HPLMN.

Answer 23

(IPLMN) Interrogating PLMN

Question 24

The user of a GSM network is referred to as the

Answer 24

Served subscribe

Question 25

the MSC that is handling the call is the serving MSC for this call; the calling subscriber is the served subscriber;

Answer 25

Mobile originated call

Question 26

the GMSC that is handling the call is the serving GMSC for this call; the called subscriber is the served subscriber.

Answer 26

Mobile terminated call

Question 27

The connections to the various entities are known as

Answer 27

Reference Points

Question 28

the connection between MSC and BSC

Answer 28

“A” Interface

Question 29

the connection between BSC and BTS

Answer 29

Abis Interface

Question 30

the connection between MSC and HLR

Answer 30

“D” Interface

Question 31

the radio connection between MS and BTS.

Answer 31

Um Interface

Question 32

MAP

Answer 32

Mobile Application Part

Question 33

is used for call control, subscriber registration, short message service, etc.; ___ is used over many of the GSM network interfaces

Answer 33

(MAP) Mobile Application Part

Question 34

BSSAP

Answer 34

Base Station System Application Part

Question 35

used over the A interface

Answer 35

Base Station System Application Part (BSSAP)

Question 36

is used between MS and MSC; DTAP is carried over the Abis and the A interface.

Answer 36

(DTAP) Direct Transfer Application Part

Question 37

ISUP

Answer 37

ISDN user part

Question 38

is the protocol for establishing and releasing circuit switched calls. ___ s also used in landline Integrated Services Digital Network (ISDN). A circuit is the data channel that is established between two users in the network. Within ISDN, the data channel
is generally a 64 kbit/s channel. The circuit is used for the transfer of the encoded speech or other data.

Answer 38

(ISUP) ISDN user part

Question 39

refers to the exchange of information for call set up

Answer 39

Signalling

Question 40

refers to the data that is transferred within a call, i.e. voice, video, fax etc.

Answer 40

Payload

Question 41

this is the GSM terminal, excluding the SIM card;

Answer 41

mobile equipment (ME)

Question 42

SIM

Answer 42

Subscriber Identification Module

Question 43

this is the chip embedded in the ___ that identifies a subscriber of a GSM network; the ___ is embedded in the ___. When the ___ card is inserted in the ME, the subscriber may register with a GSM network. The ME is now effectively personalized for this GSM subscriber;

Answer 43

(SIM) Subscriber Identification Module