Is merely speaking, accompanying, or contacting someone towards whom one feels homosexual inclinations forbidden?

If the situation is as you have described, then you must strive to free yourself and avoid mixing with this young man, being alone with him, or communicating with him by phone if it leads to a forbidden act. His feelings are not to be considered as long as the matter has reached the point you mentioned. And supplicate frequently to Allah to grant you chastity and protect you from the whispers of Satan.