ACA Cheat Sheet 2026

The 30 highest-yield ACA facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which AudioCodes mechanism prevents toll fraud by limiting the number of concurrent calls from a single SIP registration? → Call Admission Control (CAC) per IP Group or User
2. On a Mediant gateway, what does a 'proxy set' configuration define? → A group of SIP proxy servers with load balancing and redundancy settings
3. What does 'T.38' protocol support on an AudioCodes gateway enable? → Real-time fax transmission over IP networks using a dedicated fax-over-IP protocol
4. Which AudioCodes feature can detect when an incoming SIP REGISTER request uses a spoofed 'From' header and block it? → SIP Sanity Checks / Malformed SIP detection
5. Which AudioCodes gateway feature allows automatic configuration retrieval from a provisioning server on boot? → Zero-Touch Provisioning (ZTP)
6. What type of solution does AudioCodes provide for cloud communications? → Cloud-based communication solutions
7. Which of the following is a core product offered by AudioCodes? → VoIP gateways and session border controllers
8. During an AudioCodes network capture analysis, which filter in Wireshark quickly isolates SIP signaling traffic? → sip
9. What protocol does AudioCodes use by default for remote management over a secure channel? → HTTPS
10. Which RTP header field is used by AudioCodes and VoIP devices to detect out-of-order or duplicate packets? → Sequence Number
11. In an AudioCodes HA pair, which unit is responsible for sending SNMP traps and syslog messages to the NMS during normal operation? → Only the active unit sends traps and logs; the standby suppresses these events
12. Which of the following is a valid SIP message method? → REGISTER
13. Which AudioCodes product series is commonly deployed in 1+1 HA configurations for enterprise and carrier environments? → AudioCodes Mediant series (e.g., Mediant 2000, 3000, 9000)
14. How does SIP trunking integrate with a VoIP network? → It connects the VoIP system to PSTN for external communication
15. How does SIP handle call termination? → By sending the BYE method
16. What is the main advantage of using SIP (Session Initiation Protocol) in VoIP communication? → It enables communication between different devices and networks
17. What is the main advantage of using a VoIP system over traditional phone lines? → Lower cost and greater flexibility
18. Which AudioCodes tool provides centralized management, firmware upgrades, and configuration for multiple devices? → AudioCodes One Voice Operations Center (OVOC)
19. Which AudioCodes SBC security feature rate-limits SIP messages to protect against DoS and flooding attacks? → SIP Message Policy (SIP Whitelist/Blacklist and rate limiting)
20. Which MOS (Mean Opinion Score) threshold is typically considered the minimum acceptable quality for enterprise VoIP calls? → 3.6
21. What does a SIP '488 Not Acceptable Here' response indicate during call troubleshooting? → The called party does not support any of the codecs offered in the SDP
22. Which AudioCodes CLI command shows active calls and their current state in real time? → show voip calls active
23. Which DSCP value is recommended by Cisco and widely used for marking VoIP RTP media traffic to ensure priority queuing? → EF (Expedited Forwarding, DSCP 46)
24. In AudioCodes, 'RFC 2833' (now RFC 4733) support is used for: → Carrying DTMF tones out-of-band in dedicated RTP packets separate from voice audio
25. Which certificate type does AudioCodes recommend for production TLS SIP trunks to ensure interoperability and trust? → CA-signed certificates from a trusted public Certificate Authority
26. What is AudioCodes known for? → Developing voice networking and media processing solutions
27. In AudioCodes access control, what is the function of an 'IP Address Allow/Deny List'? → To permit or block SIP and management traffic from specific IP addresses or subnets
28. When an AudioCodes Mediant gateway returns SIP response '503 Service Unavailable' to outbound calls, the most likely cause is: → The configured SIP proxy is unreachable or all proxy servers in the proxy set are down
29. What does VoIP stand for? → Voice over Internet Protocol
30. Which AudioCodes SBC feature translates between different SIP variants and fixes interoperability issues between heterogeneous vendors? → SIP Normalization (via Message Manipulation Rules and SIP Profile)