AT&T Internet services today suffered a major DSL outage in the upper Midwest, affecting thousands of customers.

The outage occurred as the company was upgrading its service, although a spokesman could give no more specific reason. The company also wasn’t certain how many customers were affected.

According to a customer service representative, the affected areas included Illinois, Indiana, Ohio, Michigan and Wisconsin. Service went out early Wednesday morning, and although repairs were promised at mid-morning, service was still out through at least part of the affected area through the end of the day.