Why are the keys of a calculator in descending order whereas the cell phone keys are in ascending order?

Calculators were designed after human engineering was developed which showed that was better placement. Cell phones were also, however cell phones had to mimic the placement on keys of regular phones, which was designed before human engineering. A better example is the QWERTY keyboard on computers. This was taken from typewriters and the placement of the keys is not very good in relation to the frequency the keys are used. The QWERTY design is probably over 100 years old.