Since 424 covers parts of Los Angeles, I wondered whether entertainment companies and newer startups commonly use it. Or do most established businesses still prefer older 310 numbers?

Many established Hollywood agencies, old-school studios, and celebrities still cling tightly to their legacy 310 numbers as a status symbol. However, with the 424 overlay being around for two decades, tons of newer tech startups in Silicon Beach and modern entertainment companies use it now. It's completely normal across Santa Monica and Venice. If you are trying to verify a local business line, you can use this website https://searqle.io/phones/424/ to check the details. Ultimately, a 424 number is just as common for a thriving LA business today as a 310.