At some point they want you to switch to a business account.

Hi, @hephaestusanford​! You've got the number right -- the maximum number of voice lines possible on T-Mobile ONE is 12. We appreciate the ask! Have you hit the line limit? Is there something else we can do to help?

- Marissa

Hi - I understand this is a super old post - but I have the exact same question. Has it changed for t-mobile ONE plans, what is the maximum lines one account can have? 
 

I read it is possible to add 13+ lines just require deposits for one year. If so, how many lines after 12th with deposit?

Like to confirm. 

thank you.

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