awkward silences dont exist .
nothing is awkward unless you make it awkward.
if silence arises just ask some random questions.
whats your favorite color.. "pink" awww thats so lame so your a lovey dovey girl... go back to the roots. even if shit don't make sense just go with it.
when a "awkward" silence comes into play its most likely because you aren't comfortable with the person yet. how do you get to be more comfortable with a person? ask more questions about that person and start more conversations. if she told you she didnt like to be called over the phone i would respect that and not call. infact that could be a good way to get to know her on a deeper level. id ask her to go into more detail on why its awkward to her.
you had asked is she's shy or indecisive. all i read was excuses. sure she could be shy over the phone, in this day an age people text more then they chat over the phone, its not the norm like 10 years ago.
its just your FB dude i wouldn't over think the situation. after a day that she has added you i would ask "did you get everything you were looking for
" play around with her a little.
https://www.facebook.com/photo.php?v=72 ... =2&theater
check this video out
CHAT
I've added her on fb but to me its just pointless, I would have preferred to instead meet again. I asked for advice to see what you guys think and most of you said ''add her'' so yeah thats what i did 
ive always liked face to face more.