The Consumerist says yes, citing federal statute 18 U.S.C. Sec. 2511(2)(d). I'm not going to try to parse the legalese -- suffice it to say that the blog thinks it's made a case.

Further, Consumerist says the only time a caller has to say he or she is recording is when calling a call center in your home state if you live in California, Connecticut, Delaware, Florida, Massachusetts, Maryland, Michigan, Montana, New Hampshire, Pennsylvania, or Washington. Any other time, including making state-to-state calls, "You can secretly record to your heart's delight."

The issue came up when a Consumerist reader complained that T-Mobile refused to talk to him (company policy, they said) when he announced that he, too, was recording the call for quality assurance purposes. Consumerist's riposte? "Next time, just don't tell them."