Same question as before, just refined?

I love this girl in another country and we communicate through the phone but cannot speak each other's languages perfectly but enough to talk. The problem is that we can go minutes at a time without one word being spoken, which is so much more awkward than it sounds. We begin by greeting each other, then the useless questions about how we are doing in ___( whatever situation that person is in) then the silence comes. I'll try to ask her a question about something and then she will answer briefly: yes, no, don't know. I then try to ask her an open-ended question but she answers that briefly and will not expand on it. Then she say," Please say something, anything." but she hasn't even tried. In these six years, this problem has only gotten worse and only temporarily gets better when we see each other in the summer but only slightly better. I want this relationship to last but I am so scared that this communication problem could destroy everything. What about when we get older or married?