As per the large service center, and have multiple departments for every service. T mobile ensure different number for every other service, so as a user we can directly contact the right expert. But not always we remember all the numbers, like who to call for this specific issue. Thatâ€s why for a convenient purpose, you dial 611 to directly contact them. By this number you stayed connected to customer service of T mobile, let them know all your issues then after listening to all your problems, they will try to figure out to connect you with a specific expert in that department. The whole process with take some time, dialing 611 is not the correct option when you need to sort out your issue in a limited time. But yes if time is not a problem for you, then you will dial 611 and let them know about all your issue and make them correct.