This paper reports on the suitability of IEEE 802.11b networks for carrying real-time voice traffic, considering particularly the end terminals. More specifically we looked at such networks in different operating circumstances: an outdoor environment, an office environment, and the influence of competing traffic. Additionally we have investigated the link protocol in combination with the application layer. Based on over 2500 recorded sessions, it can be generally concluded that the 802.11b protocol can support real-time voice; particularly if the link transmission rate is immediately lowered after an unsuccessful initial transmission. However, we did find situations where the voice quality deteriorated below commonly accepted values, such as when competing with high-rate TCP traffic, when intervening obstacles blocked the transmission path, and with certain uses of the RTS/CTS mechanism.