"[A person who pretends to have...principles, that he or she does not actually possess, especially a person whose actions [contradict] stated beliefs. ][1]" is:

>a hypocrite.

Dictionary.com

Please note that this is a strong word.

Calling someone a hypocrite could carry strong connotations.

But it sounds like you want a strong word for this :D.

Meanwhile, some other words which also may or may not be strong depending on the situation and tone of voice are: [a phony][2] and [a fake][3].

Also see the comments below if you only want to talk about a person who says one thing and then says the opposite the next day (as in your first example about hating and liking to talk on the phone).

  [1]: http://%20http://www.dictionary.com/browse/hypocrite
  [2]: https://www.google.com.tw/search?q=phony&ie=utf-8&oe=utf-8&client=firefox-b-ab&gfe_rd=cr&ei=cG3KWI7WL8z48AeYlr6oCw
  [3]: http://www.thefreedictionary.com/fake