These numbers have changed over the years. For a long time, the ratio was 50|50|50 meaning 50% of leads converted to appointments, 50% of appointments converted to shows and 50% of shows converted to sales. During the last five years, the new ratio used by most is 33|67|67 where 33% of leads to appointment, 67% appointment to show and 67% show to sale. This resulted in a shift in closing ratios from 12-13% to 14-15% overall closing ratio.
Phone ups should result in appointments that show 40-45% of the time or better.