From the WWAN Settings section, click the "WWAN Preferred Mode" dropdownmenu then select the desired option.
Global is the preferred setting and allows you to access LTE and multiple global network bands.
For issues connecting to a GSM network, you can select 'HSPA only' as a troubleshooting step.
Click Save (located in the lower-left).
If HSPA only was selected in step 3, ensure the HSPA/GSM Mode is set to HSPA/UMTS + GSM (GPRS EDGE).
The preferred international carrier is automatically selected. You can manually tap an alternate carrier but it may require as many as six registration attempts with that carrier prior to successful registration.
The device restarts.