Spain’s FON pioneered the homespot model, which has proved so powerful for some broadband providers like Comcast and Iliad/Free. The notion of having a home access point with a second SSID, left open for passers-by to use, provided a low cost way to expand WiFi coverage rapidly and cheaply, using existing home lines as backhaul. But the money in service provider WiFi now lies not just in rapid roll-out but in improving the quality of experience those networks support. That is likely to be the motivation for FON’s latest acquisition, of WiFi management platform provider XCellAir. XCellAir was founded as an inhouse project at InterDigital, which then spun it out as an independent start-up in 2015. The firm developed a…