Usually, it should not be a greet problem, especially in this era of mass communications. Sometimes, it more useful to communicate via email or leave voice messages, however your advisor will be able to indicate the best way of communication with him. One should not be shy, it is especially important for foreign students, who sometimes experience difficulties with their English, and do not want to sound awkward. One should understand that your communication with your tutor and advisor is one of the most important parts of your dissertation writing process, and one that should be prepared thoroughly in order to make all process successful.
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