10 days ago, T-Mobile upped the maximum number of lines a customer could have on their Simple Choice Family Plan. Instead of the old 5-line limit, customer would be able to add up to 10 lines depending on credit status. The first 6 lines would be available to many customers, and lines 3-6 on the lowest Simple Choice plan would only cost $10 each to add to an account. Then, lines 7 through 10 would cost $20 each and would be available to customers with good credit status, and long-serving T-Mo subscribers. Seemingly, 10 days is a long time in the tech world and T-Mo has decided to cut the price of those additional lines in half.

In its announcement today that it would be offering extra data for customers signing up to tablet plans, T-Mo also announced that it would be increasing the maximum line limit to 10 lines.

Under the not-so-old plan from 10 days ago, if you took the lowest Simple Choice plan which currently offers 2.5GB of data until 2016, you’d pay $200 per month for 10 lines. Under the new plan, launching tomorrow, you’ll be able to get 10 lines on the low plan for just $160. That’s $80 for the first two lines, then $80 total for the next 8 lines. An internal communication to T-Mobile staff reads as follows:

“Yesterday we kicked off the week with an announcement about how we are quadrupling data on Simple Starter plans. Not only is it exciting news for single line customers looking for a no-frills wireless experience, it showed our competition what unbelievable value in wireless looks like. Today we are announcing two ways we are keeping family and business plans simple and affordable for every line to get more out of wireless:

1. Beginning August 27, 6-10 add-a-lines will be reduced from $20 to $10 per line, per month. That means that lines 3-10 are all just $10 per line MRC! Simple!

2. Starting September 3, a new promotional $10 per line data feature will launch giving each line 4.5GB of 4G LTE data on a Data StrongTM network! Affordable!

How We Keep Family Plans Simple

While other carriers keep customers guessing how much data the whole family is going to use, we, in true Un-carrier fashion, have lowered the add-a-line pricing and offered even more affordable data! With low cost add-a-lines, individual 4G LTE data buckets, and no domestic overages, T-Mobile makes wireless shopping simple and your monthly bill predictable. Here’s how!

Low Cost Add-a-Lines

Back on August 16, we took our family plans from good to great by expanding from a 5 line limit to up to 10. On August 27, we are taking family plans from great to unbelievable by lowering the cost of 6-10 add-a-lines from $20 to $10 per line MRC on Simple Choice! That means lines 3-10 are all just $10 per line per month! That’s simple!

Classic Family Plans will also see a decrease in the MRC of the add-a-line on 6-10 line Family Plans. The per line price for these accounts will drop from $30 to $20 per line per month! Everyone can join in on the savings!”

Of course, this deal doesn’t take in to account the EIP payments on mobiles and tablets you might also have running. Depending on devices, those could soon see your monthly commitments rocket upwards. But as a standalone plan, $160 for that many lines with that much data is awesome.

Update: T-Mobile’s official spiel on the matter doesn’t break it down as specifically.