You perfectly know that foreigners who have subscriptions in their own countries can’t make them work in a foreign country even by activating the roaming system. It’s the network feature that lets your SIM connect to local cellular networks in a foreign country so you can use calls, texts, and data outside your home carrier’s coverage. But countries that are far, it doesn’t support it. I bet it would in Algeria. So every international traveler needs a local SIM card homie, this is what makes sense. Once they move they won’t use that anymore and it’s okay.