A person buys a mobile phone from a store provided the seller gives him a SIM card
The kind of transaction mentioned is impermissible because it includes a loan that brings about benefit, since you lend someone the SIM card fees (Part No. 11; Page No. 135) to make him buy the mobile phone from you.
And since every loan that brings about benefit is Riba (usury), you have to abandon this kind of dealing and repent sincerely to Allah and never do that again.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.