Is installment money considered usury (riba) because the woman's husband was the one who handed the money to the seller in a transaction to buy a phone in installments?

This transaction is impermissible, unless it is structured as a Murabaha to a party ordering a purchase. This would entail the woman first buying the phone for herself. Once she owns it, she then sells it in a separate transaction to the man for a known price payable at a known future date. Otherwise, the true nature of the transaction will lead to usury (Riba), because it would be considered as if she lent the man the price of the phone immediately, with the condition that he repays more than he took, later, in installments.