I'm using a PnP modem which works just fine when I set it up under wvdial (run manually), but when running rp3 to dial in, it never dials but instead assigns a ppp(n) device with IP 10.111.112.113. The behavior is the same whether I select the GUI or set it to activate at boot.
This is also a problem with an external modem (which works fine on 6.2 + all updates). I also found that doing an ifup ppp0 (or whichever of the dialup interfaces I select ) causes the same problems.
You've enabled "demand-dialing" mode. From the advanced properties tab, uncheck the "bring link up and down automatically" box.