Bismillah
As salam Alykom
u mean he prounced talaq (divorve) because she went back home, although originally he agreed on that??
If this is the case, then he can not divorce because he already agreed on that. For marriage is based on fulfilling the contract conditions. But if he divorced her for something else. Let us know exactly.
Plus as far as I know wallahu a`alem, I think taking her back thru the phone is not acceptable.
I was put in a similar situation with a sister here in Egypt when the husband took her back on the phone, we checked with a scholar who said. It can be fine but he has to come and sort of have a relation with her in few days.
So just give us more details.