Same here UUCP setup to trigger syncing of nightly billing runs on SCO(!) Unixware servers.
All the code was written as a combination of Microfocus COBOL and hairy shell-scripts. I recall we had a lot of random SSH-tunnels being held open via keep-alive-pings, and SLIP was definitely something I had to use.
UUCP was handy because you could push files and run remote commands on a batch schedule without a lot of scripting. We did have some clients that had more complicated setups where we would have to resort to SLIP (serial line IP) and more traditional scripts/rsh/etc. All terribly insecure, with plain text passwords in files...or worse, ".rhosts" files.