Each Clan should have their own means to contact: LINE, FB, Whatsapp and etc.
Only by adding the Clan's contacting method, will you truly be considered a member of the Clan, and a friend.
When your Mansion is under attack, while you are asleep. Your clan members will contact you thorough Messenger App first or sending reinforcement and ask you to activate the Truce.
When attacking, you can first arrange the time for the attack and then the target on Messenger App. Since the game is all about team work, thus rally is the most efficient way.Would you attack alone or attack as a group？
As you spend more time in the game and release that you're in the same city, same district. You might start a new type of friendship.
By joining a good clan and adding the clan's contact method, you might just be adding a new chapter to your daily life.