Attempting to upload data (via ftp and/or smtp) over about 2K in size causes the modem to hang up. However, progress bar displayed (from kconqueror (KDE 2.0)) shows transfer is completed, though the pop-up does NOT go away and the ppp is effectively dead - In my case the kpppd dialog pops up along with alerts that modem has hung up (SIGHUP 16). R. Clint Ellis
Please verify this with a newer version of Red Hat Enterprise Linux or Fedora Core and reopen it against the new version if it still occurs. Closing as "not a bug" for now.