The VOIP system is another matter - they often cause cost overruns, true, but only when installed by someone who doesn't know what they're doing. It all depends on the product and the company installing it. In most cases a properly engineered VOIP system can save money and give the same 5 nines reliability of TDM.
Misleading statements like this are what causes the thinking that a VoIP system is going to save money. There is absolutely no reason to have an IP system unless there are multiple sites with a dedicated WAN between them. Even then there is no cost savings and actually an increased cost to using IP phones for a number of reasons.
Now that we have the facts straight let's not turn this topic into a TDM vs VoIP debate!
-Hal
