Why can't I add a voice line to my T-Mobile One account online?

nyree

    I have a T-Mobile One account with 3 lines. I want to add a 4th line and purchase an iPhone 7.  However when I click on "Add a Line", it tells me I'm not eligible to add any voice lines,only up to 5 mobile device lines. Do I have to go into a store to do this?

      All replies