Not sure if this is a version specific issue, or a problem with some tweaks I made, but on my current renpy version, 8.2.3.24061702, the phone steps dialogue forward a step between the relationships screen, and the phonePal screen, despite both being modal.
Quick hacked together fix I've managed, change all numbered instances of
Call("phonePal", 1, girl1_name, girl1_love, girl1_lust, girl1_dominance, girl1_submissive, girl1_pregnant)
to
Show("central_stats", girl=1, name=girl1_name, love=)girl1_love, lust=girl1_lust, dominance=girl1_dominance, submissive=girl1_submissive, pregnant=girl1_pregnant)
It's a bit messy, but I believe that should work nearly as well as your the current implementation and it gets rid of the problem for me.