A VoIP connection is different from other services. When you use your browser, for example, the only thing you need is good network speed. You will never realize if some packets have different paths or their incoming sequence is different from the source. Therefore, bandwidth is the only parameter you need to care about.
TestYourVoIP gives you a MOS value of a simulated VoIP call (MOS scale has 1 to 5 levels. Level 5 is the best quality). You can see how these values are different for several locations and depending on what time you call. MyVoIPSpeed test shows you some connection parameters (jitter, packet loss) and the resulting overall call quality. Both of these services can be an excellent way to do pre-deployment and post-deployment VoIP connection monitoring.