Jessica: "We Laugh About Carrie!"

Jessica Simpson is fighting to save face after rival blond Carrie Underwood claimed a certain Dallas Cowboys Quarterback still calls her behind Jess's back!

"The phone will ring and it will be him, and maybe I won't answer," Carrie says of her ex Tony Romo in the September issue of Allure Magazine.

Jessica then took to the airwaves, insisting that her boyfriend does not call the "Before He Cheats" singer, despite what Carrie claims.

"I looked at his call log," Jessica, 28, told a Nashville Radion station on August 20.  "Tony and I both laughed at that.  We got a chuckle out of it."

But Carrie's friends insist it's Jess who should be embarrassed.  As OK! exclusively reported in May, Tony is still very much in contact with Carrie.  "They talk and text regularly," the source said.  "They broke up as friends so there's no reason for them not to talk."

The source also says Jessica is well aware that they talk.  "But," says the source, "She's not happy about it."

In the meantime, it looks like the rivalry between the two blondes will continue.  Jessica is set to release her first country album, Do You Know, on Sept. 9, and both women are expected to attend the CMA Awards on Nov. 12.

But a friend of Carrie's says the Grammy winner is far from concerned. 

"She'd love to see Jess try and come close to the success she's had," says the friend.  "She doesn't think she has the God-given talent.  Carrie thinks Jess is a big bottle of bleach and a pair of high-heeled cowboy boots trying to ride off the fame of Newlyweds."

Ouch!

For the full story on Jessica vs. Carrie, pick up the new OK!--on sale everywhere on Thursday!