Using the SIM Toolkit to switch between UK and EU mode

The below is tested on a Nexus 5, as this is what I have.. details for iPhone etc. will be similar but different.

As shipped the SIM is in UK mode, which means it behaves exactly the same as a standard UK SIP2SIM.

On Android, in the app drawer a new app will have become visible called 'SIM Tool Kit'.
On the iPhone the SIM Toolkit can be accessed via Settings > Phone > Sim Applications.

When you select this you get the options on the SIM:

Multi-Account
- Country Selection
  - UK
  - Roaming
- Set Global Fallback
  - Enabled
  - Disabled

To enable the EU roaming feature select 'Roaming'. You then have to select a non-O2 provider in (android) Settings > Mobile Networks > Network Operators. You must do this quickly otherwise the SIM will see the O2 connection and switch itself back to UK mode, and you have to start again (it's not obvious where the blame lies for this bug!).

To switch back to UK either select UK in the country selection or select O2 in the network operators list.

At the present time it is unknown what the 'Set Global Fallback' option does.

Up to RoamingSIMs

Nexus 6 & Missing SIM Toolkit

(June 2015) one of the recent Android updates to the Nexus 6, seems to have lost the 'SIM Toolkit' application. It appears that the SIM lock *must* be enabled for the SIM Toolkit to appear (on the Nexus 6, anyway). Somewhat annoying, since it's now necessary to enter the PIN twice (once for the Android OS - necessary for full device encryption), and once for the SIM. But at least it works