In this paper, we analyzed VoIP data rates to minimize the bandwidth efficiently as per user demand and reduced the budget cost before implementing VoIP service at any wired and wireless network. To accomplish these results different clock rates were used to assign bandwidth administratively, CODEC schemes (G.711 and G.729) to minimized data rates and QoS (Quality of Service) such as CBWFQ and 802.11e to sustain the voice quality in congestion over the wired and wireless networks. PRTG Grapher and LAN Traffic Generator software were used to monitor a bandwidth and create congestion artificially between the link of communicating two setup LANs wired and wireless.