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The performance of wireless LANs is greatly affected by pathloss, RF interference and other sources of signal attenuation, in addition to network congestion. The primary factors involved in effective real-time communication, namely delay and loss, must be within certain controlled limits in such a scenario. In this paper, we analyze the various factors driving IEEE 802.11 b access points through extensive simulations and thereafter develop an optimization technique to configure the parameters of the access points. We simulate our test bed scenario and apply the developed algorithm. We then implement the configured parameters in our SIP enabled test bed to provide optimum Voice over IP (VoIP) performance. Thereafter, we further analyze and optimize the parameters of the communicating nodes being realized through Xlite soft phones that enhance VoIP performance to a much better extent both for voice and video calls. Test bed results confirm an improvement from 22% packet loss to 3% considering both AP and node configurations together. Finally, we propose optimization algorithm for proper selection of threshold parameters in active queue management system. Results verify significant performance improvement in VoIP under congested scenarios. Simulation and measured results have also been included.