I use these two highly effective software solutions for what you are looking for:
QuickLink? MessageCenter is an integrated voice, fax and data communication software program that lets your users receive voice mail and exchange faxes and data files with remote modems, fax/modems, and fax machines quickly and easily.
http://www.smithmicro.com/wab/qlmcoem.tpl
Simply BitWare is the revolutionary new release of the top selling BitWare messaging product suite from ACCPAC. Simply BitWare takesall the fax power of Simply BitFax and adds in feature-rich benefits that give you advanced integrated voice and paging capabilities.
http://www.accpac.com/products/communication/bitware/bitware_32bit.asp