Is a telephone conversation that includes indecency considered zinā (illicit sexual relations), and is there expiation for it?

What you did with this young man, including forbidden acts and phone conversations containing indecency, is considered reprehensible and unlawful. You must repent to Allah and sever the relationship immediately. What occurred is considered zina (fornication/adultery) in a general sense, based on the Prophet's (peace be upon him) saying: "The two eyes commit zina by looking, the two ears commit zina by listening, the tongue commits zina by speaking, the hand commits zina by striking, the foot commits zina by walking, and the heart desires and wishes, and the private parts either confirm or deny that." As for the zina that mandates a legal punishment, it is the insertion of the glans into the private parts. The expiation for this is sincere repentance, performing good deeds, observing the obligatory prayers, and abstaining from prohibitions, because "Indeed, good deeds do away with evil deeds."

As for your father's refusal to complete the marriage due to the suitor not possessing citizenship, this is not a legitimate reason to reject a suitor. Try to convince your father, otherwise you have the right to take the matter to the Sharia court if his refusal is without acceptable justification. You should know that your statement about not being able to give up the young man is not befitting of a Muslim woman. Rather, you should supplicate for the marriage to him to be facilitated if it is good for you, otherwise, it is obligatory to convince yourself to let him go.