WLANs are now widely used for internet access. In the wireless domain there are still many challenges to overcome before VoIP could become a reliable replacement to traditional telephones. For the IEEE 802.11 WLAN, \\\\cite{Wang} proposes a scheme in order to increase the number of simultaneous VoIP sessions that the network can hold. QoS in VoIP is an important issue. Using the suggested scheme, we make an investigation of the number of VoIP sessions that the network can retain without excessive degradation of QoS, and make a comparison of the improvement obtained using the suggested scheme.