Your tablet is set to connect to 3G networks only

I can't make voice calls

1
Find "Network mode"
- Slide your finger down the display starting from the top edge of your tablet.
  Press the settings icon.
- Press Mobile networks.
- Press Network mode.
2
Select network mode
- Press LTE/WCDMA/GSM (auto connect), WCDMA/GSM (auto connect), WCDMA only or GSM only.
- 3G (UMTS) or 4G (LTE) enables you to achieve higher data speeds than when using 2G (GSM). If you select LTE/WCDMA/GSM (auto connect), your tablet automatically switches between the three network modes provided that you're within range of a 4G network. If you select WCDMA/GSM (auto connect), your tablet automatically switches between the two network modes provided that you're within range of a 3G network. If you select WCDMA only, your tablet can only connect to 3G networks. If you select GSM only, you can't achieve high data speeds.
3
Return to the home screen
- Press the Home key to return to the home screen.

Did this solve your problem?

1
Find "Network mode"
- Slide your finger down the display starting from the top edge of your tablet.
  Press the settings icon.
- Press Mobile networks.
- Press Network mode.
2
Select network mode
- Press LTE/WCDMA/GSM (auto connect), WCDMA/GSM (auto connect), WCDMA only or GSM only.
- 3G (UMTS) or 4G (LTE) enables you to achieve higher data speeds than when using 2G (GSM). If you select LTE/WCDMA/GSM (auto connect), your tablet automatically switches between the three network modes provided that you're within range of a 4G network. If you select WCDMA/GSM (auto connect), your tablet automatically switches between the two network modes provided that you're within range of a 3G network. If you select WCDMA only, your tablet can only connect to 3G networks. If you select GSM only, you can't achieve high data speeds.
3
Return to the home screen
- Press the Home key to return to the home screen.