The Persist="no" line in /etc/sysconfig/network-scripts/ifcfg-ppp0 no longer works. The modem keeps dialing and dialing until kill -9 all the processes.
PERSIST is case-sensitive. "Persist" won't work, and never would have.
PERSIST="no" doesn't work either
PERSIST defaults to "no". I've never seen this problem. I just tested it here, both without any PERSIST line at all, and with PERSIST=no, and in both cases, it doesn't persist. I need more information. Now, PERSIST has *nothing* to do with redialing if the connection was never established. PERSIST only is queried if the connection was up in the first place and then came down.