Verizon Communications agreed to buy Hughes Telematics for $612 million in cash, vaulting the telephone company deeper into the automotive-technology market.

Verizon will pay $12 a share in the acquisition, which is expected to close in the third quarter, the company said yesterday.

Atlanta-based Hughes sells products that offer GPS tracking, communications and safety features in cars. The deal gives Verizon a new source of growth as it faces saturation in the US market for mobile phones and land lines. Verizon is competing with carriers like AT&T and other companies such as Apple, which sells both devices and services.

Hughes offers voice and data connections to vehicles that are monitored through call centers. The system provides emergency services and vehicle diagnostics. Hughes closed at $11.79. Verizon fell 1.5 percent to $41.03.