Is it permissible for a telecommunications company to deduct 3% of the purchase value when paying a merchant via mobile, or is that considered usury?

If the telecommunications company pays the price on behalf of the customer from his account for a fee of 3% of the amount, there is no harm in this, as it is a wage for a known service. It is permissible to use debit cards, which deduct directly from the customer's balance, as long as the bank is not usurious and the fees paid are for services provided by the bank. It is also permissible to use them to purchase gold and other items for which immediate possession is required, because the deduction occurs at the time of purchase. However, if the company lends the price and collects it with a 3% increase, this is a matter of dispute, and its ruling is similar to that of an unsecured credit card.