What is the ruling on purchasing a mobile phone at a symbolic price from Western telecommunications companies, such that it only accepts the SIM card of that company, and then unlocking it to use in another country? And what is incumbent upon one who participated in this, if it is impermissible?

If the phone manufacturer stipulates that the phone should not be unlocked, and this condition affects the phone's price by reducing it, then this condition must be fulfilled, based on the Prophet's (peace be upon him) saying: "Muslims are bound by their conditions in what is permissible." Whoever participates in unlocking it must repent, and the phone owner must compensate the manufacturer for violating the condition.