'RHOA' Star Porsha Williams -- Demotion Was No Big Deal ... But We Don't Believe her

Porsha Williams SAYS she's not fazed by her recent demotion on "Real Housewives of Atlanta"... but she sounds like she's lying.

Porsha was at LAX Thursday when she told our photog her dance card is filled with work now that she's no long a series regular, but watch the video ... it just doesn't ring true.

We broke the story ... Porsha was demoted back in October from main cast member to friend for being a pain in the ass.