jrockfl - 9:14 pm on Apr 16, 2013 (gmt 0)
I use the Endicia Label Server API to calculate postage and to print shipping labels for USPS.
This will allow me to create a shipping label and also get a tracking number.
The tracking number is saved in the orders database table. I can then call a different web service and pass it the tracking number it will return the tracking details.