I was on five waitlists this summer, and went to South America for two months. I came off Georgetown's waitlist right before I left, I bought an international cell phone and Dartmouth called me about a week after I got here on my international number, Colorado e-mailed me a couple of days later, and Baylor called my mom and them e-mailed me last Thursday.
I e-mailed all of my schools, told them my situation, updated my AMCAS and the schools to say they could give my mom myinfo, and kept addresses and phone numbers updated. You should be fine!