You can enable data roaming on your iPhone by following the path below:
Settings > Mobile data > Mobile data options > Data roaming > select “ON“
You are ready to use your Transatel DataSIM and stay connected around the world. Please make sure that you have inserted the SIM card on your device, configured the APN settings and enable data roaming. For faster connection speed, make sure that the network mode is set to 4G/LTE.
See detailed procedure on our userguide: https://www.transatel-datasim.com/wp-content/uploads/2017/08/tds201703_userguidea4_sim_en.pdf