Comment 13 for bug 1470835

Tony, about: “My guess is that this is an instance of the multiple networks being present for the same carrier. When you select the one that doesn't roam, the modem switches you automatically to the network with better signal.”

Disable roaming for operator A in System Settings. If operator B appears on the network, System Settings can't do anything to stop ofono from roaming on B's network.

Isn't a global roaming switch the answer here? System Settings' not a daemon, so it can only disable roaming for the networks it knows while used by the user.