Which of theses network characteristics is commonly associated with an echo on a VoIP connection?

Which of theses network characteristics is commonly associated with an echo on a VoIP connection?

• Propagation delay
• Signal capture and regeneration from link to link
• Packet queue delay
• Connection latency 

EXPLANATION

Here are the factors that tend to cause VoIP latency:

• You lack sufficient bandwidth. When an internet connection is slow, data packets take more time to flow to and fro. This causes quality to suffer. Often, the packets arrive in the wrong order, which makes reassembly impossible unless the order is restored. This is one of the disadvantages of packet switching, which VoIP uses.
• Your firewall might be blocking traffic. Checkpoints are always a bottleneck, so make sure you allow clearance for your VoIP apps within the firewall software.
• The wrong codecs are being used. Codecs are programs used to encode voice signals into digital data for transmission over the network, and your provider might be using the wrong one. You can't do anything about that; however, if you're using a VoIP app that allows you to tweak codecs, try changing them.
• You're using old hardware. Old hardware with new software or new networks might not work that well, and delay and latency are often a result. Try using a different telephone adapter or phone (if you are using an IP phone or any other VoIP-specific hardware). Your hub also might be a culprit. Headsets often cause latency, too.

• Your system might be converting the signal to or from analog or digital.
• Buffering is causing audio latency. Buffering occurs when audio data is being transferred and when there's a difference between the time of transmission and reception.