Customer ask us...If we go with the VOIP phone system does that mean we the quality will be poor?
The answer is, not neccessary.  It really depends on how, when, and where you are using the voip functionality.  Let's say for example, if you are just replacing a traditional phone system with an Allworx Voip Phone System and all phones are on the local lan, then should NOT have poor quality on the phones.  This is because the amount of bandwidth on the local lan most of the time exceed the requirement for a clear conversations.  The challenge is normally with remote phones.  Let's say, you have an office in Austin with one remote user in Dallas.  There is a percentage that the remote user may experience a bit poorer quality on the phones as the remote phones will be going through the internet.  Look on the bright side, there are options that can help us resolve this issues.
1.  We can implement WAN technology that have options for Gurantee Quality of Services such as T1, Point-to- Point T1, MPLS, Frame Relay, etc.  These technology may be a little bit more expensive the the traditional dsl or cable modem.  Depending on how many user will be using this technolgy, the cost can be justifiable. 
2.  We can use a less expensive internet connection than T1, Point-to-Point T1, MPLS, and Frame Relay such as dsl or cable modem and install a bit higher end router that can support QoS (Quality of Services).  Keep in mind, even though the router support QoS, we are still on the mercy of the internet, so this solutions would still be consider best effort only.  It's kind of like a cell phone, we sacrifice a bit of quality for flexibility and portability.  Depending on expectations, this can be a very affordable and acceptable solutions!  The internet is much faster now then it was 10 years ago, so most of the time, it is perfectly fine.
3.  We can implement plug and play.  Basically, you take the phone to a remote location (home or office) configure it as a remote phone, and simply program no QoS.  This to me, is really considered best effort or no effort at all.  As usual, depending on expectation, this solutions may work perfectly fine!