Phones are ringing off the hook at law offices serving immigrants with shaky status. Some of Trump’s promises, such as the border wall, would require a good deal of time and money to implement as well as possibly requiring approval from Congress. Trump’s pledge to reverse executive actions issued by Obama, on the other hand, could be authorized in late January, shortly after Trump takes office, said Stephen Yale-Loehr, a professor of immigration law at Cornell Law School in Ithaca, N.Y.