This is a advanced new VoIP router with all rich features. Pls check DrayTek web site at :
Vigor2500V router equipped with QoS function : Automatic QoS Assurance Traffic levels from your local users to the Internet can vary; if someone else on your router is downloading, that will affect your speeds. Mostly that's quite tolerable - you just get your data a little slower but you wouldn't normally notice. With VoIP, things are different. A voice call has to be digitised, transmitted to the remote end and the turned back into an analogue waveform (sound!) in real-time. If part of a packet is delayed then the sound becomes jerky and intermittent which at best is annoying and in worst cases intolerable. The Vigor2500V firstly uses efficient codecs designed to make the best use of available bandwidth, but secondly includes automatic QoS Assurance. QoS (Quality of Service) Assurance reserves part of your Internet bandwidth for voice calls whilst a voice call is active (the reserved bandwidth is available for regular use if there is no Voice call active). This means that, regardless of what else other people are doing on your Network, you will always have the necessary inbound and outbound bandwidth reserved exclusively for Voice.
Just for your info.