Disabling 3G dongle roaming & failover to another 3G dongle

I guess this has been questioned thousand times, but I can’t get the answer.

Is it possible to disable 3G roaming with a 3G dongle / miniPCIe card on Mikrotik ? It doesn’t look so. Would it be possible with some scripting ?

I would like to make a switchover / failover to another 3G card when I cross the border and the home signal is lost.

So 2 3G dongles on Mikrotik, locked to home operator and Mikrotik switching between them based on availability of home signal.

Thanks !