Cell phone call curiosity

Apropos of nothing much--I've gotten several robo-phone calls in Chinese from Chicago and LA numbers. We don't pick up, but they leave a message. The family cell phone numbers are sequential, and one of the others gets them too. Chinese spam can't be that cost-effective in the USA.

Probably it's targeted advertising--sort of like the East Coast college emails I've been getting for a year that are actually intended for a high school junior. Cheer for the almighty algorithm!