As an organization, GSMA is a European trade body that represents the interests of approx. 800 mobile network operators worldwide. It produces a number of important industry events. Apart from Barcelona, there is Mobile World Congress Shanghai, Mobile World Congress Americas and Mobile 360 Series.
The Barcelona Congress happens to be the largest annual mobile-focused exhibition and conference in the world.
Quite frankly I have been in awe of the size, the hustle and mega brands exhibiting their over-the-top displays of grandeur and dominating pricey floor-space vs nearby competitors!