You can claim trademark on anything you like. You can threaten legal action over the claimed mark. You can start litigation over the claimed mark. These facts d

You can claim trademark on anything you like. You can threaten legal action over the claimed mark. You can start litigation over the claimed mark. These facts do not mean you have grounds to win. Registering a mark gives you better protection and drastically increases your odds of winning against an alleged infringer. Registering numbers, AFAIK, still is not allowed.