NCS 30022252010 NCSP 2G 3G SCN OaM 2 2 Practice
Exam
**Question 1.** Which core network element is primarily responsible for
switching voice calls in a 2G circuit‑switched network?
A) SGSN
B) GGSN
C) MSC
D) HLR
Answer: C
Explanation: The Mobile Switching Center (MSC) handles call routing, setup, and
release for circuit‑switched voice services in 2G networks.
**Question 2.** In a 3G PS core, the interface that connects the SGSN to the
GGSN is known as:
A) A interface
B) Gn interface
C) E interface
D) Gb interface
Answer: B
Explanation: The Gn interface (or Gn/Gp for GTP) carries user plane traffic
between the SGSN and GGSN.
**Question 3.** The HLR stores which of the following subscriber data?
A) Real‑time packet statistics
, NCS 30022252010 NCSP 2G 3G SCN OaM 2 2 Practice
Exam
B) Permanent subscriber profile and authentication keys
C) Temporary routing area updates
D) Media gateway configuration
Answer: B
Explanation: The Home Location Register holds the subscriber’s permanent
profile, IMSI, and authentication credentials.
**Question 4.** Which SS7 protocol provides routing and addressing for
messages across the network?
A) MTP
B) SCCP
C) TCAP
D) ISUP
Answer: B
Explanation: The Signalling Connection Control Part (SCCP) adds routing,
addressing, and segmentation to the basic MTP transport.
**Question 5.** SIGTRAN is used to transport SS7 over which type of network?
A) Ethernet LAN only
B) IP‑based networks
C) Satellite links
, NCS 30022252010 NCSP 2G 3G SCN OaM 2 2 Practice
Exam
D) MPLS backbones only
Answer: B
Explanation: SIGTRAN encapsulates SS7 messages in IP packets, allowing SS7 to
run over IP networks.
**Question 6.** The protocol that tunnels user‑plane and control‑plane packets
between SGSN and GGSN is:
A) SIP
B) GTP‑C and GTP‑U
C) MAP
D) Diameter
Answer: B
Explanation: GTP‑C (control) and GTP‑U (user) are used for tunneling between
SGSN and GGSN.
**Question 7.** Which interface connects the MSC to the Base Station Controller
(BSC) in a 2G network?
A) A interface
B) B interface
C) C interface
D) D interface
Answer: A
, NCS 30022252010 NCSP 2G 3G SCN OaM 2 2 Practice
Exam
Explanation: The A interface carries signaling and traffic between MSC and BSC.
**Question 8.** In a 3G network, the HSS replaces the HLR. What additional
function does the HSS provide?
A) Packet routing only
B) Policy and charging control (PCC) support
C) Media conversion
D) Physical layer encryption
Answer: B
Explanation: The Home Subscriber Server (HSS) integrates authentication with
policy and charging control functions.
**Question 9.** A “Call Setup Success Rate” KPI is calculated as:
A) (Successful call setups ÷ Total call attempts) × 100%
B) (Dropped calls ÷ Successful calls) × 100%
C) (Total voice minutes ÷ Peak load) × 100%
D) (Failed handovers ÷ Total handovers) × 100%
Answer: A
Explanation: CS KPI for call setup success is the ratio of successful setups to total
attempts.
Exam
**Question 1.** Which core network element is primarily responsible for
switching voice calls in a 2G circuit‑switched network?
A) SGSN
B) GGSN
C) MSC
D) HLR
Answer: C
Explanation: The Mobile Switching Center (MSC) handles call routing, setup, and
release for circuit‑switched voice services in 2G networks.
**Question 2.** In a 3G PS core, the interface that connects the SGSN to the
GGSN is known as:
A) A interface
B) Gn interface
C) E interface
D) Gb interface
Answer: B
Explanation: The Gn interface (or Gn/Gp for GTP) carries user plane traffic
between the SGSN and GGSN.
**Question 3.** The HLR stores which of the following subscriber data?
A) Real‑time packet statistics
, NCS 30022252010 NCSP 2G 3G SCN OaM 2 2 Practice
Exam
B) Permanent subscriber profile and authentication keys
C) Temporary routing area updates
D) Media gateway configuration
Answer: B
Explanation: The Home Location Register holds the subscriber’s permanent
profile, IMSI, and authentication credentials.
**Question 4.** Which SS7 protocol provides routing and addressing for
messages across the network?
A) MTP
B) SCCP
C) TCAP
D) ISUP
Answer: B
Explanation: The Signalling Connection Control Part (SCCP) adds routing,
addressing, and segmentation to the basic MTP transport.
**Question 5.** SIGTRAN is used to transport SS7 over which type of network?
A) Ethernet LAN only
B) IP‑based networks
C) Satellite links
, NCS 30022252010 NCSP 2G 3G SCN OaM 2 2 Practice
Exam
D) MPLS backbones only
Answer: B
Explanation: SIGTRAN encapsulates SS7 messages in IP packets, allowing SS7 to
run over IP networks.
**Question 6.** The protocol that tunnels user‑plane and control‑plane packets
between SGSN and GGSN is:
A) SIP
B) GTP‑C and GTP‑U
C) MAP
D) Diameter
Answer: B
Explanation: GTP‑C (control) and GTP‑U (user) are used for tunneling between
SGSN and GGSN.
**Question 7.** Which interface connects the MSC to the Base Station Controller
(BSC) in a 2G network?
A) A interface
B) B interface
C) C interface
D) D interface
Answer: A
, NCS 30022252010 NCSP 2G 3G SCN OaM 2 2 Practice
Exam
Explanation: The A interface carries signaling and traffic between MSC and BSC.
**Question 8.** In a 3G network, the HSS replaces the HLR. What additional
function does the HSS provide?
A) Packet routing only
B) Policy and charging control (PCC) support
C) Media conversion
D) Physical layer encryption
Answer: B
Explanation: The Home Subscriber Server (HSS) integrates authentication with
policy and charging control functions.
**Question 9.** A “Call Setup Success Rate” KPI is calculated as:
A) (Successful call setups ÷ Total call attempts) × 100%
B) (Dropped calls ÷ Successful calls) × 100%
C) (Total voice minutes ÷ Peak load) × 100%
D) (Failed handovers ÷ Total handovers) × 100%
Answer: A
Explanation: CS KPI for call setup success is the ratio of successful setups to total
attempts.
