APN Settings

If you have the "LTE SIM":

Settings > More > Cellular networks

Enable "Data roaming", and dismiss its warning.

Tap Access Point Names

Tap "+" to add a new entry

Name: FreedomPop
APN: fp.com.attz

Tap 3-dots and tap Save.

Select the new FreedomPop entry.

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If you have the "Global SIM":

Settings > More > Cellular networks

Enable "Data roaming", and dismiss its warning.

Tap Access Point Names

Tap "+" to add a new entry
Name: FreedomPop
APN: freedompop.foggmobile.com

Tap 3-dots and tap Save.

Select the new FreedomPop entry.