FedEx Ground's tracking numbers have different digits: 12, 15, 20, 22.
12-digits tracking numbers use mod 11 algorithm. Others use mod 10 algorithm.
But recently I got some 20-digits FedEx Smartpost tracking numbers which can't identified by both algorithms.
So, how can I identify these tracking numbers?
Sample tracking numbers: 7489999873402038xxxx 6129270107532465xxxx
I figured this out.
see: http://images.fedex.com/us/software/pdf/FedEx_SmartPost_Job_Aid_v2600_06222012.pdf https://www.pdffiller.com/en/project/10655396.htm
22 digits tracking numbers remove 2 digits application identifiers (91 or 92). We need add application identifiers to the tracking numbers before mod 10 algorithm.
The 20 digit codes need either 91 (old) or 92 (new) before the code. Pre-pend those and apply a standard mod-10 algorithm used by the IMpb standard.