3CX Basic Certification Exam Prep
Document 2025/2026 | PBX
Administration, VoIP, SIP Trunking &
System Configuration Exam QUESTIONS
AND VERIFIED ACCURATE SOLUTION
(DETAILED & ELABORATED) |GET IT 100%
ACCURATE!! 2026 TEST
1. What is the primary purpose of a PBX?
A. Store customer records
B. Route and manage telephone calls within and outside an
organization
C. Monitor network traffic
D. Manage email servers
Answer: B
Rationale: A Private Branch Exchange (PBX) manages internal
and external voice communications by routing calls
efficiently.
2. What does VoIP stand for?
A. Voice over Internet Program
B. Video over IP
C. Voice over Internet Protocol
D. Virtual Online Internet Phone
,Answer: C
Rationale: VoIP transmits voice communications over IP
networks instead of traditional telephone lines.
3. Which protocol is primarily responsible for establishing
VoIP calls?
A. HTTP
B. FTP
C. SMTP
D. SIP
Answer: D
Rationale: SIP (Session Initiation Protocol) establishes,
modifies, and terminates multimedia sessions.
4. RTP is primarily responsible for:
A. Email delivery
B. Database synchronization
C. Transporting voice media during calls
D. DNS resolution
Answer: C
Rationale: RTP carries real-time audio and video streams
once a SIP session has been established.
5. Which default port does SIP commonly use over UDP?
,A. 25
B. 443
C. 5060
D. 8080
Answer: C
Rationale: SIP commonly uses UDP/TCP port 5060 and TLS
port 5061.
6. Which protocol encrypts SIP signaling?
A. FTP
B. SSH
C. TLS
D. ICMP
Answer: C
Rationale: TLS secures SIP signaling, protecting call setup
information.
7. Which codec generally provides the highest voice quality?
A. G.729
B. GSM
C. G.711
D. iLBC
Answer: C
Rationale: G.711 offers uncompressed audio with excellent
voice quality but requires more bandwidth.
, 8. G.729 is preferred when:
A. Maximum bandwidth is available
B. Bandwidth is limited
C. Recording calls
D. Using analog phones only
Answer: B
Rationale: G.729 compresses voice significantly, making it
suitable for low-bandwidth environments.
9. Which device converts analog phones into SIP devices?
A. Layer 3 Switch
B. SBC
C. ATA
D. Firewall
Answer: C
Rationale: An Analog Telephone Adapter (ATA) enables
analog phones to connect to VoIP systems.
10. What does SBC stand for?
A. Secure Broadband Controller
B. Simple Business Communication
C. Session Border Controller
D. System Backup Controller
Answer: C
Document 2025/2026 | PBX
Administration, VoIP, SIP Trunking &
System Configuration Exam QUESTIONS
AND VERIFIED ACCURATE SOLUTION
(DETAILED & ELABORATED) |GET IT 100%
ACCURATE!! 2026 TEST
1. What is the primary purpose of a PBX?
A. Store customer records
B. Route and manage telephone calls within and outside an
organization
C. Monitor network traffic
D. Manage email servers
Answer: B
Rationale: A Private Branch Exchange (PBX) manages internal
and external voice communications by routing calls
efficiently.
2. What does VoIP stand for?
A. Voice over Internet Program
B. Video over IP
C. Voice over Internet Protocol
D. Virtual Online Internet Phone
,Answer: C
Rationale: VoIP transmits voice communications over IP
networks instead of traditional telephone lines.
3. Which protocol is primarily responsible for establishing
VoIP calls?
A. HTTP
B. FTP
C. SMTP
D. SIP
Answer: D
Rationale: SIP (Session Initiation Protocol) establishes,
modifies, and terminates multimedia sessions.
4. RTP is primarily responsible for:
A. Email delivery
B. Database synchronization
C. Transporting voice media during calls
D. DNS resolution
Answer: C
Rationale: RTP carries real-time audio and video streams
once a SIP session has been established.
5. Which default port does SIP commonly use over UDP?
,A. 25
B. 443
C. 5060
D. 8080
Answer: C
Rationale: SIP commonly uses UDP/TCP port 5060 and TLS
port 5061.
6. Which protocol encrypts SIP signaling?
A. FTP
B. SSH
C. TLS
D. ICMP
Answer: C
Rationale: TLS secures SIP signaling, protecting call setup
information.
7. Which codec generally provides the highest voice quality?
A. G.729
B. GSM
C. G.711
D. iLBC
Answer: C
Rationale: G.711 offers uncompressed audio with excellent
voice quality but requires more bandwidth.
, 8. G.729 is preferred when:
A. Maximum bandwidth is available
B. Bandwidth is limited
C. Recording calls
D. Using analog phones only
Answer: B
Rationale: G.729 compresses voice significantly, making it
suitable for low-bandwidth environments.
9. Which device converts analog phones into SIP devices?
A. Layer 3 Switch
B. SBC
C. ATA
D. Firewall
Answer: C
Rationale: An Analog Telephone Adapter (ATA) enables
analog phones to connect to VoIP systems.
10. What does SBC stand for?
A. Secure Broadband Controller
B. Simple Business Communication
C. Session Border Controller
D. System Backup Controller
Answer: C
