I. Introduction
VOIP applications have replaced traditional phone services because of the rich advantages they offer including sound clarity, cost saving for businesses and usage simplicity. A major advantage of VoIP over Public Switched Telephone Network (PSTN) is the uncharged or low rate for both national and international calls. Another feature that VoIP offers is the higher voice quality. Unlike PSTN that encodes up to 8 KHz, some VoIP applications maintain 16 KHz [1]. Corporations can cut costs for their network infrastructure by having a single standalone network to serve both data and voice, rather than having two different networks. The availability and ease of use of VoIP has also attracted people that have little technical background to use the technology in their communications.