Is merely greeting or asking about relatives over the phone considered sufficient in maintaining kinship ties with those who do not reciprocate visits, especially if visiting them causes distress due to their lack of connection?

Do not respond to the ill-treatment of relatives with ill-treatment. Rather, continue to maintain ties with them and show them kindness, for the true maintainer of ties is one who connects with those who have cut him off. It is enough for you that you suppress their anger and prevent harm from reaching them, and Allah's help will remain with you against them. The one who maintains ties is not he who reciprocates, but rather he who connects with the kin that have cut him off. A greeting or a phone call is considered the lowest form of maintaining kinship ties and severs estrangement, but do not limit yourself to it. For by maintaining kinship ties, sustenance increases, lifespans are extended, and Allah Almighty connects with you, and He has prepared a great reward for you in this world and the Hereafter.