My phone is still locked under rogers. I flashed my phone few times now try to find the best combo, and I haven't run in to any problem yet. from what I read and understand flashing and you sim card are to different things. they shouldn't be interfering with each-other. I now using a Taiwan main, fs, and hong kong custom file. I didn't have any problem with sim card at all or with the phone. so i'm sure it will be ok for you too...