Voice over IP A Discussion of Business and IT Challenges

What is IP Telephony? IP Telephony uses VoIP standards to create telephony systems which offer all the features of a traditional private branch exchange (PBX) systems, as well as a range of integrated new software applications which can increase functionality and productivity. These productivity applications, such as advance call routing, unified messaging, interactive voice response system, and call center applications are modular and tightly integrated through the use of industry standard protocols. Some examples of these protocols are SIP, H.323, MGCP, and SGCP. The definitions of these protocols are outside the scope of this study. To find out more about these you may visit IETF website.3 Illustration below is a basic IP Telephony setup:

Figure 2: Basic IP Telephony setup There are four basic components in an IP Telephony system namely, IP Phone, Data Switch, IP PBX, and a Voice Gateway. All of these components are connected to the data network. In a simple setup, a user dials a telephone number using an IP Phone. This telephone number is sent to the IP PBX. If the number was an internal extension then IP PBX sends the call to destination IP Phone. However, if the number was for a party outside of company then IP PBX sends the call to the Voice Gateway which dials outside party through PSTN(Public Switched Telephone Network).