Why does the Device not make certain calls?

During use the device will not make calls for example to International numbers, Check if Fixed Dialling Numbers (FDN) is enabled:
1. Go to the phone menu and select settings
2. Select Fixed Dialling Numbers (FDN)
3. In this screen you can enable/Disable FDN, you will need to know the PIN2 code. You can also manage the list of FDN from this page