The selected network mode is not available - Telstra Dave

I can't make voice calls

1
Find "Network Mode"
- Slide your finger down the display starting from the top edge of your phone.
  Press the settings icon.
- Press Mobile networks.
- Press Network Mode.
2
Select network mode
- Press GSM/WCDMA/LTE, GSM/WCDMA auto, 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 GSM/WCDMA/LTE, your phone automatically switches between the three network modes provided that you're within range of a 3G or a 4G network. If you select GSM/WCDMA auto, your phone automatically switches between 3G and 2G provided that you're within range of a 3G network. If you select WCDMA only, your phone 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 phone.
  Press the settings icon.
- Press Mobile networks.
- Press Network Mode.
2
Select network mode
- Press GSM/WCDMA/LTE, GSM/WCDMA auto, 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 GSM/WCDMA/LTE, your phone automatically switches between the three network modes provided that you're within range of a 3G or a 4G network. If you select GSM/WCDMA auto, your phone automatically switches between 3G and 2G provided that you're within range of a 3G network. If you select WCDMA only, your phone 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.