What common voice issue can occur on the PSTN due to network delay?

The common voice issue that can occur on the PSTN (Public Switched Telephone Network) due to network delay is echo. Echo happens when a person's voice is transmitted across a network and then reflected back to them, often due to latency in the network.

When there's a delay in the transmission of voice signals, the speaker may hear their own voice delayed by several hundred milliseconds or more. This can occur when the voice is sent along a longer route to reach its destination, or when the signals are being processed and converted through different network technologies. The delay creates an overlap, causing the speaker to hear an echo of their own voice.

Understanding this phenomenon is crucial for troubleshooting and improving communication quality over any telephony system utilizing the PSTN. Other issues such as static interference, latency, and dropouts may affect voice quality but are distinct from the echo effect that's specifically linked to network delay.