Is it obligatory for a Muslim expatriate who is still a student or dependent to maintain lawful contact with all his relatives, taking into consideration that some of them do not ask about him, the cost of communication, and their large number? And must this contact be periodic?

Allah has commanded the strengthening of kinship ties (silat al-rahim), and the Lawgiver has not specified the extent or nature of this connection. Therefore, it is determined by custom (urf). The obligation of maintaining ties is not contingent on relatives inquiring about the person, as the Prophet, peace and blessings be upon him, said: "The one who maintains ties is not the one who reciprocates, but the one who maintains ties is he who, when his kinship ties are cut off, connects them." This obligation is tied to one's ability, so what a person is unable to do is waived. Kinship ties have various levels, the lowest of which is refraining from desertion and offering greetings (salam). These levels vary according to ability and need, with some being obligatory and others recommended. Connection can be established through visiting, writing, or contacting.