http://www.telecomdirectnews.com/do.php/150/9857?4798
Open Source PBX on VoIP!!! Amazing!

Read Accounting fundaes again today :-)
Gross Profit - Revenues from Core operations - Direct costs (e.g. raw material cost...)
Operating Profit = Gross Profit - Operating Expenses (Salaries, Rent, Power...)
Net Profit = Operating Profit + Other Income - Depreciation - Interest - Taxes
Retained Earnings = Net Profit - Dividends.