Existing smartphones will connect with new satellite constellations in 2023
SpaceX and T-Mobile are starting a trial in late-2023 
to use unmodified handsets for text (and later, voice and data) with the Starlink V2 network to remove cell coverage dead-zones. [1] [2]It's achieved by "dedicating a slice of T-Mobile's Mid-Band PCS [1.9 GHz] spectrum, to be integrated into Starlink satellites, launched next year", with each Starlink V2 satellite hosting two 5-6 meter long cell-spectrum antennas, in addition to the existing Ka- and Ku-band antennas.They're aiming for the US with the trial, and growing to global coverage by entering into reciprocal roaming agreements with the international carriers who hold licences to the relevant mid-band spectrum.Elon Musk says "this won't have the kind of bandwidth that a Starlink terminal would have, but it will enable texting. It will enable images. And if there aren't too many people in the in the cell-zone, you could even potentially have a little bit of video."Musk claims 2 to 4 megabits per cell-zone, 1000-2000 simultaneous voice calls per cell-zone, with the cell-zone of course being much larger than a terrestrial cell-tower.[1] https://www.t-mobile.com/news/un-carrier/t-mobile-takes-cove...[2] https://youtu.be/F8zS2rU-URo?t=325