When creating a ppp connection using rp3, if you edit the connection and
change any of the advanced settings, the connection. It appears to grab
settings from somewhere other than /etc/sysconfig/network-scripts or
/etc/wvdial.conf:

Jul 31 22:01:24 merlin pppd[3902]: pppd 2.3.11 started by root, uid 0
Jul 31 22:01:24 merlin pppd[3902]: Using interface ppp1
Jul 31 22:01:24 merlin pppd[3902]: local  IP address 10.64.64.65
Jul 31 22:01:24 merlin pppd[3902]: remote IP address 10.112.112.113
Jul 31 22:01:29 merlin pppd[3902]: Terminating on signal 2.
Jul 31 22:01:29 merlin pppd[3902]: Exit.

It never talks to the modem once you edit the connection settings, however,
if you select the connection and use 'debug' mode, it connects properly.
I'm unable to find where it's grabbing the 10.x.x.x ip addresses from in
any of the configuration files in /etc.

If you create the connection and then edit the connection settings by hand
instead of using rp3 to edit them, rp3 will be able to dial in and connect
fine with the changed settings.