In this report, we present an analytical model for VoIP capacity in IEEE 802.11e WLAN. We illustrate performance results relative to typical codec rates of G.711 PCM (64 kbit/s), G.729 (8 kbit/s) and G.723 (6.3 kbit/s). G.729 and G.723 allow a greater capacity than G.711 which is constrained by throughput. This greater capacity is at the expense of small quality degradation due to the delay increase since G.729 and G.723 codecs are more delay sensitive than G.711. In our study we analyse the occurrence of CAPs (Controlled Access Periods) during the Contention Period (CP) and its effect of a promising increase in the VoIP over WLAN capacity. We also show that high data rates (up to 54 Mb/s) allow important VoIP capacity (up to 400 G.711 VoIP calls, 997 G.729 VoIP calls and 1045 G.723 VoIP calls).