We have tested WiFi phones and laptops handing over on cafenet, it works OK at low speeds, but is not totally seemless. However with surfing and even voice the slight delay while layers 2 and 3 sort themselves out is near to inperceptible. There are some proprietary features in some APs that can smooth handover. We have not set about to create seemless handover, but with out trying it appears to be not too bad. Generally the client tries to hold a link with an AP until a signal threshold is reached and then the client looks for the best signal again. I have not tried to tweak any parameters to optimise this process. Some client cards appear to perform better than others, but again we have not specifically tested that.