Users will be able to send texts and images where cell coverage does not currently exist, key for emergency situations in remote areas, Musk said at a flashy event on Thursday at his company's south Texas rocket facility.
"The thing that I think is really profound about what we're announcing today is that it will save lives and we will no longer read about these tragedies that happened where people got lost, and if only they could have called for help, they'd be okay," Musk said.
Starlink's satellites will use T-Mobile's mid-band spectrum to create a new network. Most phones used by the company's customers will be compatible with the new service, which will start with texting services in a beta phase beginning by the end of next year.
SpaceX has launched nearly 3,000 low-Earth-orbiting Starlink satellites since 2019, handily outpacing rivals OneWeb and Amazon.com Inc's Project Kuiper.
SpaceX's next-generation Starlink satellites, the first of which are planned to launch on SpaceX's next-generation Starship rocket whenever it is fully developed, will have larger antennae that will allow connectivity directly to mobile phones on the T-mobile network, Musk said.
"We are constructing special antenna. ... They are actually very big antenna that is extremely advanced," he said. "The important thing is you will not need to get a new phone. The phone you currently have will work."