Are the free minutes offered by telecommunication companies in exchange for a sum of money deposited into their bank account considered forbidden Riba (usury) because they are in exchange for a loan, or are they permissible since they are not of the same kind as the deposited amount?

If the amount deposited in the company's account is a loan, then the gifts given to customers in exchange for this deposit are considered forbidden usury (riba).

It was narrated from the Prophet, peace and blessings be upon him: "If one of you gives a loan, and the borrower gifts him something or gives him a ride on his mount, he should not ride it nor accept it, unless there was a prior customary exchange between them."

Abdullah ibn Salam also said to Abu Burdah: "If you have a right over a man (i.e., he owes you a debt), and he gifts you a load of straw, or a load of barley, or a load of fodder, do not accept it; for it is usury."

Ibn Qudamah mentioned that every loan that stipulates an increase is forbidden. It is not permissible for the borrower to offer a tangible item or a benefit to the lender because of the loan, unless there was a customary practice between them before the loan.