3CX Basic Certification Exam Prep Document 2026/2027 | PBX
Administration, VoIP, SIP Trunking & System Configuration
Verified Questions with Detailed Rationales
1. What is the primary role of a PBX?
A. Store email messages
B. Manage internal and external phone calls
C. Route web traffic
D. Provide cloud storage
Answer: B — A PBX switches and manages telephone calls.
2. Which protocol is most commonly used by 3CX for call signaling?
A. HTTP
B. FTP
C. SIP
D. SMTP
Answer: C — SIP handles VoIP call setup and control.
3. What does SIP stand for?
A. Secure Internet Protocol
B. Session Initiation Protocol
C. System Integration Process
D. Subscriber Interface Port
Answer: B.
4. In 3CX, what is an extension?
A. A firewall rule
B. A SIP trunk
C. A user's phone identity
D. A voicemail server
Answer: C.
,5. Which transport is commonly used for SIP?
A. UDP
B. ICMP
C. ARP
D. GRE
Answer: A — SIP often uses UDP 5060.
6. What is a SIP trunk?
A. A physical copper cable
B. A virtual connection between PBX and provider
C. A voicemail account
D. A VPN tunnel
Answer: B.
7. Which port is the default SIP port in many deployments?
A. 80
B. 443
C. 5060
D. 3389
Answer: C.
8. RTP is primarily responsible for:
A. User authentication
B. Voice media transport
C. DNS resolution
D. File transfer
Answer: B.
9. What is NAT in networking?
A. Network Access Tunnel
B. Network Address Translation
C. Node Authentication Table
D. Native Audio Transport
Answer: B.
10. Which DNS record is often used to locate SIP services?
, A. A
B. MX
C. TXT
D. SRV
Answer: D.
11. In 3CX, a ring group is used to:
A. Block spam calls
B. Ring multiple extensions together
C. Encrypt calls
D. Configure SIP trunks
Answer: B.
12. What does an IVR do?
A. Records calls only
B. Provides automated menu options
C. Routes email
D. Manages DHCP
Answer: B.
13. Which codec is widely used for compressed VoIP audio?
A. G.711
B. MP3
C. WAV
D. FLAC
Answer: A — G.711 is common and high quality.
14. A DID number is:
A. A voicemail PIN
B. A direct inward dialing number
C. A SIP password
D. A firewall port
Answer: B.
15. What is the purpose of voicemail?
A. Encrypt calls
Administration, VoIP, SIP Trunking & System Configuration
Verified Questions with Detailed Rationales
1. What is the primary role of a PBX?
A. Store email messages
B. Manage internal and external phone calls
C. Route web traffic
D. Provide cloud storage
Answer: B — A PBX switches and manages telephone calls.
2. Which protocol is most commonly used by 3CX for call signaling?
A. HTTP
B. FTP
C. SIP
D. SMTP
Answer: C — SIP handles VoIP call setup and control.
3. What does SIP stand for?
A. Secure Internet Protocol
B. Session Initiation Protocol
C. System Integration Process
D. Subscriber Interface Port
Answer: B.
4. In 3CX, what is an extension?
A. A firewall rule
B. A SIP trunk
C. A user's phone identity
D. A voicemail server
Answer: C.
,5. Which transport is commonly used for SIP?
A. UDP
B. ICMP
C. ARP
D. GRE
Answer: A — SIP often uses UDP 5060.
6. What is a SIP trunk?
A. A physical copper cable
B. A virtual connection between PBX and provider
C. A voicemail account
D. A VPN tunnel
Answer: B.
7. Which port is the default SIP port in many deployments?
A. 80
B. 443
C. 5060
D. 3389
Answer: C.
8. RTP is primarily responsible for:
A. User authentication
B. Voice media transport
C. DNS resolution
D. File transfer
Answer: B.
9. What is NAT in networking?
A. Network Access Tunnel
B. Network Address Translation
C. Node Authentication Table
D. Native Audio Transport
Answer: B.
10. Which DNS record is often used to locate SIP services?
, A. A
B. MX
C. TXT
D. SRV
Answer: D.
11. In 3CX, a ring group is used to:
A. Block spam calls
B. Ring multiple extensions together
C. Encrypt calls
D. Configure SIP trunks
Answer: B.
12. What does an IVR do?
A. Records calls only
B. Provides automated menu options
C. Routes email
D. Manages DHCP
Answer: B.
13. Which codec is widely used for compressed VoIP audio?
A. G.711
B. MP3
C. WAV
D. FLAC
Answer: A — G.711 is common and high quality.
14. A DID number is:
A. A voicemail PIN
B. A direct inward dialing number
C. A SIP password
D. A firewall port
Answer: B.
15. What is the purpose of voicemail?
A. Encrypt calls
