My wife does a ton of long-distance intrastate calling. The rates are significantly better and the entire package with call waiting, call forwarding, etc . . . is a lot cheaper.
We installed a VOIP system at the office for our outbound LD
and it cut our monthly telephone bill from $9,000 per month to $1,100. Of course we've got to amortize the cost of the new equipment but the payback is less than one year.