Satellite radio provider Sirius has reached the 500,000-subscriber benchmark, the company said today (July 14).

Satellite radio provider Sirius has reached the 500,000-subscriber benchmark, the company said today (July 14).

"This is another major milestone for SIRIUS, as we continue to grow our business," says CEO Joseph P. Clayton in a statement. "In the second half of the year, we expect to attract many additional subscribers."

The company is expanding its retail presence this year and expects to triple the amount of stores that sell its products to more than 20,000. Personal technology chain RadioShack is starting this month to carry the Orbiter model Sirius receiver alongside mobile and home docking stations and a boombox attachment.

Rival XM Satellite Radio topped 2.1 million subscribers in its most recently released numbers.