ASUS isn't known for offering its tablets to North American carriers with 3G or 4G; an FCC filing for a cellular-capable Transformer Pad TF300 could be a clue at a break in the WiFi-only trend. Along with the usual wireless, a TF300TL variant of the Android 4.0 slate has stopped by the agency with the 850MHz and 1,900MHz frequencies needed for HSPA 3G as well as, best of all, 700MHz and 1,700MHz support for LTE-based 4G. All four are what we'd look for in an AT&T-oriented tablet, so don't be surprised if Ma Bell carries a 4G Transformer Pad before long. All but the 700MHz band would be handy for Canadian networks as well. There's no surefire evidence of when the tablet might make a more formal appearance, nor hints of whether or not it will keep the quad-core Tegra 3, although the slight spin on the regular TF300 formula could keep the wait short.