How can one atone for selling a phone that was found, when its owner is known but lives in another country and cannot be contacted?

Whoever finds a lost item is obliged to safeguard it and announce it for a full year. However, a phone does not require this due to the ease of reaching its owner. Repentance for using a phone you found without announcing it involves regretting the action, resolving not to repeat it, and returning the right to its owner. If you can reach him, apologize and inform him so he may forgive or demand his right. If you wish to keep it discreet, convey his right to him indirectly. If you cannot reach him, donate its value on his behalf. If you later find him, inform him or deliver his right to him.