Sounds like what you said...something immediately came up and she didn't have a chance to tell anyone. I guess there's nothing you can really do...just wait until she calls or writes or something.
However, the phone deal sounds creepy...even though it being shut off obviously means that she intended on being away for an extended period of time, so I would take that as a good sign
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Not to pry, but are you two an item? If not, that's probably why she didn't call. She may only have had time to call family etc. I know you're worried, and I hope she turns up soon. Keep us posted!