He divorced her three times over the phone

Divorce (talaaq) over the phone is a valid divorce and counts as such. So long as the husband uttered the word of divorce (talaaq), divorce has taken place. 

There is a difference of opinion among the scholars with regard to the threefold divorce; the majority are of the view that it counts as three divorces. 

A number of scholars are of the view that the threefold divorce counts as one divorce. This is the view favoured by Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) and it was regarded as more correct by Shaykh al-Sa‘di and Shaykh Ibn ‘Uthaymeen (may Allah have mercy on them both). 

They quoted as evidence the report narrated by Muslim (1472) from Ibn ‘Abbaas (may Allah be pleased with him) who said: At the time of the Messenger of Allaah (blessings and peace of Allah be upon him), Abu Bakr and the first two years of ‘Umar’s caliphate, a threefold divorce was counted as one. Then ‘Umar ibn al-Khattaab said: People have become hasty in a matter in which they should take their time. I am thinking of holding them to it. So he made it binding upon them. 

See also the answer to question no. 36580. 

According to this opinion, it is permissible for your husband to take you back during the ‘iddah, if this was a first or second talaaq. 

And Allah knows best.