Answer
(Fatwa: 333/256/H=1434)
You gave only one talaq on phone, and you did not give any other talaq before (neither in past during nikah nor in iddah period) while the wife also confirms your statement, then one talaq took place as per the question mentioned above.
(2) You can revoke the talaq by taking it back (rujoo) if the iddah is not over.
(3) You will have to give her the maintenance and housing until the iddah is over. You will not be required to pay the same after iddah.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband