verb+ba+ii isn't really "you have to...", it's more like "it's enough to just..." or "if you (just) do this it is OK". Sometimes if people are mad at being asked to do something they might say something like "surya ii darou, surya!" which is literally "if I do it its OK isn't it, if I do it", but is more like "alright, stop badgering me, I'm going to do it, that's enough for you isn't it, shut up!"
There is a sense in which there is an element of "you have to" - they are saying "all you have to do is...", which implies that while you do have to make the contact, you don't have to do anything more, like ask again for a reply, keep waiting, etc. etc.
kamuizero said:
Mayonaka ni futo megazameru to itai hodo no seijaku
itsu no manika kanojo no koe mo tozasare
fushigi na mahou ni miserareta boku wa kodomo no you ni
kanojo wa mou *rajio* totomoni nemuri ni tsuita
Erm something like...
Suddenly waking in the middle of the night, it's so quiet it hurts
I didn't notice when her voice was silenced
Entranced by some strange spell, I'm like a child again
She had already fallen asleep with the radio
Ha ha, I wish I'd had the brains to do a Google search for the kanji BEFORE I translated it, but anyway it's here:
https://web.archive.org/web/20040612033622/http://cct2.st.toba-cmt.ac.jp/~8421/newpage20.htm
. J/K Actually, I'm even less sure about the use of "katte ni."
.
, it's in romaji:
