Why Surfroam uses Slot 1?

In dual-slot smartphones, you have to put Surfroam SIM into Slot 1.
It is guaranteed that the SIM card will be activated correctly and registered in a network as fast as possible.
Also, it helps to make the setup process simple and handy.
Slot 2 supports "simple SIM's," local SIM's and SD cards, in many cases depending on manufacturer device Slot 2 does not support new smart SIM technologies.
Slot 1 supports all types of SIM's, including "smart" SIM's with more memory and functions.
Your local SIM will work fine in slot 2 during your next travel. 

You may choose in settings which slot serves as data only channel and the second one is for calls and messages.