It may take several seconds to hear what the other person has said. Users of a poorly implemented VoIP solution will encounter a similar delay. A typical IP packet will transit through multiple hops or routing devices, with each device imposing a variable amount of delay. The network delay is the total accumulated delay. However, such schemes are based on nascent technology that may not be available in the targeted networks.
Long delays exacerbate a problem known as line echo.
Echo is not always bad. As long as the round-trip delay is less than 50 ms and the echo is not too loud, it is acceptable. Beyond 50 ms, however, echo becomes intrusive. The standard is defined in International Telecommunications Union specification G.131. But because of network delay, the delay in IP networks can be much higher.