CHICAGO (Reuters) - J.P. Morgan on Wednesday said it expects credit-rating agencies Moody's Investors Service and Standard & Poor's to cut their ratings on wireless telephone company AT&T Wireless Services Inc. (NYSE:AWE - News).

Analyst Thomas Lee said in a research note that the magnitude of the downgrade is not known but the two agencies could possibly cut the No. 3 U.S. wireless company to below investment grade.

"Rating agencies have been slashing their ratings on telecoms, with a recent focus on wireless," Lee said. "(There is) no immediate implication for AT&T Wireless but the company will have to carefully manage cash."

He said a downgrade could further worsen the negative credit cycle that has gripped wireless companies in the past few weeks.