Same thing as in the xml_cdr.php page display. If the call is answered instantly, less than a second, then the difference is 0s, and the 0s is a visual indicator that the call was answered, it just took less than a second. Calls that didn't get answered have a large negative number stored in the TTA field, 0 is an answered call.
* Updates for CDR archives database server
* Add CDR Archive Server
* Updates for CDR archive server
* Updates for CDR Archive server
* Updates for CDR Archive server
* Create xml_cdr_archive.php
Cause all the .php files containing lines ending with \r\n to instead end with \n.
DYI with:
find fusionpbx -type f -name '*.php' -exec dos2unix '{}' \;