PRS* VOIP may be the right solution for you. Because it is based on Open Source technology, PRS* is between ½ to ¾ the price of comparable, proprietary phone systems. Plus you won't get hit with hardware and software maintenance costs year after year.
You might think that for this kind of price you would get a phone system with limited functionality, but that's not the case. PRS*, based upon Asterisk Open Source, has a very deep level of functionality - and in many cases, more functionality than far more costly high-end systems.
With PRS* you don't have to pay high prices for a "big" name phone system. You pay less, and you get a lot more.
PRS is an Authorized Digium Reseller.