They use their phones to order supplies, get market prices for their meat, or talk to their kids in school. (Nomad kids board in dormitories in towns during the school year.) And like everyone else on the planet, they have a bit of music and games loaded for fun. Where mobile coverage is lacking I’ve seen nomads use walkie talkies to connect with neighbors or even to coordinate a roundup of livestock. If they have coverage, they use their phones while on horseback.
Far more ubiquitous than mobile phones are solar LEDs. Every ger has its panels and batteries. The panel (usually one) is simple, tied to a pole, which can be rotated by hand every now and then to follow the sun. It will power a single LED light bulb, perhaps charge a phone and a shortwave radio. Less commonly it will power a TV with a satellite dish. Having a cheap, steady light all night makes a huge difference: It extends evenings, makes cooking more convenient, and reduces toxic smoke in the home. I did not see a ger without solar.
The third nearly ubiquitous technology in nomad lands is one of the most underappreciated transformative technologies in developing countries. Nearly every family owns a cheap motorcycle. A motorcycle functions as a substitute pack animal/bus/truck. They can carry more than a pony. Rural folk will overload them to a ridiculous degree, piling more on them then you’d ever dare put into your pickup truck. Forget about millions to engineer a road. Motorcycles can follow a footpath than no jeep or 4x4 could traverse, allowing them to penetrate the most gnarly boonies for almost nothing.