Asking for real, I've never heard of the tech.
SMS for me are a godsend. They work with every phones, every carriers. They work on terrible networks. They work in the mountains, in the country side, in the trains and cars when going fast, in many tunnels and metros. They work in crazily lost places when I travel. Once I sent a text to my father from the Dogon country, a northern part of Mali where there is only sand and a few goats.
Lost your phone ? If you can remember/find the phone number, get a cheap sim, send a text, you are back in business. No permission scheme, no auth, no friends to add or certificate. 1 SIM = 1 ID is also very convenient.
SMS is the email of phone. Limited. Primitive. Efficient. Reliable.
So if you want to replace it with something else, you need a very good story.