Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
The problem that occurs between spouses should be solved according to Shariah without hastening to utter the word 'Divorce', which people usually regret afterwards.
It is evident that you divorced your wife 3 times, because the wife's pressure, or uttering the word 'divorce' through the phone or doubting the validity of marriage, all those do not prevent divorce, from occuring. You should not have uttered the word 'divorce' to cast out the doubt in your heart, as in principle the marriage is valid unless there is something that proves the contrary.
Therefore, this divorce is irrevocable and your wife is not Halal for you unless she marries another man, who consummates the marriage with her, then divorces her or dies.
We draw your attention, however, that if there are some trustworthy people of knowledge in your country, then it would be more appropriate to refer the case to them, as they might know more about your case.
Allah knows best.