Moderator: Community Team

If there are 2 players in the game who are coordinating over the phone, then yes, it is cheating because it is not posted in chat.Rule #2: No secret diplomacy
Any form of diplomatic discussion between opponents must be posted in the game chat in a language that all opponents understand. Diplomacy includes, but is not limited to: proposing truces, negotiating alliances, and coordinating attacks. Secret diplomacy can be hard to prove, but if you suspect it you should leave the players in question appropriate ratings. If you feel certain about players engaging in secret diplomacy consider reporting them in the Cheating & Abuse Reports forum by posting a new topic.