I have a Lenovo phone with dual sims that I bought from China. I'm currently switching over carriers, and it's useful to be able to have my old SIM in for peop

I have a Lenovo phone with dual sims that I bought from China. I'm currently switching over carriers, and it's useful to be able to have my old SIM in for people and companies that haven't managed to get my new number. So yes, the option does exist, just not in the American market. It seems to be somewhat unique to the Asian market from what I've seen. It does mean that you're limited to the phones that have dual sim slots though, which tend to be less powerful than flagship phones.