Your zip code and phone number is placed on the third and fourth line respectively. (grandresume.com)
(As of this writing, Sprint offers a discounted rate on unlimited family plans, waiving charges on the third and fourth line of data through March 2019.) (tomsguide.com)
Sometimes, deals — like Sprint's current offer that waives the cost of the third and fourth line for a year — can drive that cost down. (tomsguide.com)