Global SMS are SMS sent from Singapore to overseas number and is chargeable at $0.18 per message.
If you are charged for Global SMS to UK unknowingly, it may be due to the activation of iMessage and Facetime for IOS users such as,
1. Switching on/off iCloud
2. Inserting SIM card into IOS devices (Removing and re-inserting may also trigger the activation request for iMessage and Facetime)
During the setup of iMessage and Facetime, a Global SMS is sent out in the background by your IOS device to Apple’s servers in UK to initiate the activation. In some cases, a pop up message will appear informing you that charges may be incurred.
This is a function by Apple. Triggering of Global SMS and frequency of it happening is not within the control of Grid Mobile.
Activation request is sent via Global SMS to Apple’s servers in UK; including but not limited to the following UK number:
To prevent such charges in future, you may try turning off or logging out of both your iMessage and Facetime.