Since a long time, Phone is one of main tools using by all firms in the world. This last years, with the Growth of the IT networks, telephony become including on it with the name VoIP (Voice over IP). Contrary to Public Switched Telephone Networks (PSTN), like France Telecom phone network, with private central plateforms, VoIP allows a real time transport of voice in all of analogic and numeric networks thanks to TCP/IP protocol (procol for Internet).
VoIP opens new developpement for voice and data transport. That's why, actually, we spoke about convergence between Voice and Data
This convergence simply network and telecom administration and developpement of voice and data software.
We can imagine easier all possibilities offered by a voice and data CRM application.

Second interesting thing, offered by VoIP, is economic. Lot of companies loose lot of money in phone billing (for internal call or long distance call). A price of an Internet call is ridiculous if we compare with price of a PSTN operator's call)