Which of the following reasons may cause the voice user to pick up the phone without dial tone?

Question

Options

• AExternal line failure
• BDevice port hardware failure
• CNo voice file is loaded
• DData error

• A
  100% (35)

Explanation

All four options are correct because a missing dial tone can originate from failures at any layer of the telephony system, not just one. An external line failure (A) breaks the connection to the service provider or PSTN, so no dial tone can be delivered to the handset; a device port hardware failure (B) means the physical interface - such as an FXS port - that connects the phone to the system is non-functional, preventing tone generation or passthrough entirely. When no voice file is loaded (C), the system lacks the firmware or DSP resources required to synthesize dial tone, which is a common issue in router-based or IP-PBX voice platforms; a data error (D) can corrupt configuration or system state and cause voice services to fail during initialization, also resulting in silence on pickup. Because all four describe real, distinct failure modes that each independently produce the same symptom, this is an "all of the above" question with no wrong choices.

Memory tip: Picture four layers stacked from outside to inside - Line, Hardware, Software, Data (L-H-S-D). A break at any single layer is enough to kill the dial tone, so every layer is a candidate answer.

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