"[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 note that if you the person only 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), we would normally just say that this person is [capricious][4] and [wishy-washy][5].

It is when they say one thing and *do* another that this person becomes a hypocrite.

  [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
  [4]: https://www.google.com.tw/search?q=capricious&ie=utf-8&oe=utf-8&client=firefox-b-ab&gfe_rd=cr&ei=63HKWJT9I8348Ae-1K-QDA
  [5]: https://www.merriam-webster.com/dictionary/wishy%E2%80%93washy