The free year of service offer starts Friday, Aug. 28, and runs through Sept. 30, 2015,
DirecTV customers switching to Sprint--or existing Sprint customers--can take advantage of the promotion.
The offer for existing Sprint customers is available to customers adding a new line of service through Sprint Lease, iPhone Forever, Sprint Easy Pay1, or paying full retail price for a smartphone.
The free year of service includes unlimited talk, text and 2GB of data per line (up to five lines), while the devices are used on the Sprint network.
Customers are responsible for the one-time $36 activation fee and monthly taxes and surcharges.
For new customers, Sprint will pay off existing phone and contracts, up to $300 per line.
After the promotional period, customers will pay standard rates.