T-Mobile is offering an unadvertised 50% off your monthly cellular bill for 3 months under their Stay Connected program for a limited time. This 50% discount only applies to your plan and add ons. Your plan would be capped at 3GB of data per line for the duration of the promotion. The 50% discount doesn’t apply to any installment plans. The promotion will be added to your account upon request and your account will revert back to your original plan when it expires in three months. To get this offer you can direct message T-Mobile on Twitter or call their customer service line at 1-800-937-8997 and mention the Stay Connected program.
Source: Reddit – T-Mobile