So I have had a 9900 for a year, got a new one under warranty again this year and several of my neighbours do too. We are on Rogers and it has no signal around here so we have UMA, its important to point out that we all have different 7.1 devices, different routers and service providers.
Problem is no matter what hybrid, leaked or official software we run the UMA wont lock reliably, it will connect to Wi-fi and BES/BIS but not switch to UMA or drop it on random.
it will sit in SOS, H+, GPRS, EDGE etc or off (if mobile network radio is off). Trying to make a call will fail but get the phone to go into UMA, sometimes it takes a few attempts to make a call to do this. Turning on/off wifi or Mobile network may help but not always, battery pull or rebooting may or may not help.
OS6 devices however work just great on UMA...this is frustrating, any help?