Troubleshooting & Maintenance Flashcards
6 cards from real Business Phone Systems practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Troubleshooting & Maintenance flashcards as text
What should you check if phones on a specific subnet are experiencing call quality issues while others are not?
Answer: QoS configuration on the network switch or router serving that subnet
Localized quality problems often indicate that QoS markings are not being applied or honored on the switch or router for that specific network segment.
What is a common cause of calls dropping after exactly 30 or 32 seconds on a VoIP system?
Answer: A firewall with a short SIP ALG or UDP session timeout killing the RTP stream
Many firewalls and SIP ALGs time out short-duration UDP sessions, cutting off RTP media streams mid-call at predictable intervals.
What does SIP ALG (Application Layer Gateway) do and why is it often disabled for VoIP?
Answer: Modifies SIP packets passing through a router, often corrupting them and causing call failures
SIP ALG attempts to translate SIP headers for NAT but frequently corrupts the data, causing registration failures, one-way audio, and dropped calls.
What is the recommended approach when a firmware update breaks IP phone functionality?
Answer: Roll back to the previous stable firmware version from the manufacturer's portal
Rolling back to a known-good firmware version is the fastest way to restore functionality while the manufacturer investigates the problematic update.
What information should be collected before contacting VoIP provider support about a call quality issue?
Answer: Affected extension numbers, time and date of issue, call recordings, and network test results
Specific call details, timestamps, recordings, and network test data allow provider support to reproduce and diagnose the issue efficiently.
What does a '503 Service Unavailable' SIP error response indicate?
Answer: The SIP server is overloaded or temporarily unavailable
A SIP 503 response means the server cannot handle the request due to overload or maintenance, similar to an HTTP 503 error.