Bond ratings by independent rating agencies reflect the risk associated with holding a company's bonds. In general a strong bond rating reflects confidence in the financial strength of the company.

Ratings definitions may be found on each agency's web site:

Rating Agencies

Standard & Poor's
TDS Rating BB
USM Rating BB
Moody's
TDS Rating Ba2
USM Rating Ba1
Fitch
TDS Rating BB+
USM Rating BB+