Question: how much does it cost to add another line to att?
Answer: Single Line: Plan is for one phone line only and monthly plan charge is $40 for 3 GB or $50 for 9GB before discounts. Device monthly access charge is extra. Multi-Line: Plan is for 2 to 10 lines and monthly plan charge is $60 for 3GB and $80 for 9GB. Per device monthly access charges are extra.