There's more to it than that. I had a model where voice would work on both networks but SMS would only work on one. The only contacts app you could use also rel

There's more to it than that. I had a model where voice would work on both networks but SMS would only work on one. The only contacts app you could use also relied on a proprietary gateway, and took a minute to open on the other network. Also, updates to SMS implementations eventually broke SMS on the good network.