The talk starts with a brief introduction into 802.11-based positioning systems. After presenting state-of-art scanning techniques to measure the signal strength of access points within communication range of a mobile device, the talk discusses that these scanning techniques are not sufficient if 802.11 is used for communications and positioning at the same time. A novel scanning technique called Monitor Sniffing mitigates many of the problems inherent with the current approaches. The talk closes with an overview of the so-called ComPoScan system. ComPoScan combines Monitor Sniffing and the current scanning techniques to preserve the communication capabilities of mobile devices while simultaneously allowing positioning.