"From the 17th November 2010 the following numbers are not included within the minutes or text allowance in any of our goodybags.
075201, 075207, 075597, 075890, 075892, 076696, 077000, 077001, 077442, 077443, 077444, 077445, 077446, 077447, 077448, 077449, 077552, 077553, 077554, 077555, 078220, 078221, 078223, 078224, 078225, 078226, 078229, 078644, 078727, 078730, 078744, 078745, 078920, 078921, 078922, 078930, 078931, 078933, 078938, 078939, 079112, 079117, 079118, 079245, 079246, 079780, 079781, 079784, 079785, 079786, 079788, 079789, 079118, 079112, 079879, 079785, 0871955."
http://support.giffgaff.com/app/answers/detail/a_id/552