WASHINGTON (Reuters) - The Federal Communications Commission said Thursday that it had approved 319 companies, including AT&T Inc and Comcast Corp -- to participate in a temporary $3.2 billion program funded by Congress to provide lower-income Americans with discounts on monthly internet service and on purchasing laptops or tablet computer. The discounts are worth up to $50 a month for internet service, and up to $75 on Tribal Lands. Acting FCC Chairwoman Jessica Rosenworcel said the commission would continue to approve additional providers and expected that Americans would soon be able to enroll in the program.