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Use voice domain for emergency call branding

Last Updated: 12/12/2016

To meet mobile operator requirements, OEMs can enable the voice domain to decide whether to use Emergency calls only or No service in the phone UI branding.

Constraints: FirstVariationOnly

Instructions:

  1. Create a customization answer file using the contents shown in the following code sample.

    <?xml version="1.0" encoding="utf-8" ?>  
    <ImageCustomizations xmlns="http://schemas.microsoft.com/embedded/2004/10/ImageUpdate"  
                         Name="UseVoiceDomainForEmergencyCallBranding"  
                         Description="Use to let the voice domain decide whether to use 'Emergency calls only' or 'No service' in the
                                      phone UI branding. "  
                         Owner=""  
                         OwnerType="OEM"> 
    
      <Static>  
    
        <Settings Path="Phone/PhoneSettings">  
          <Setting Name="UseVoiceDomainForEmergencyCallBranding" Value="" />
        </Settings>  
    
      </Static>
    
    </ImageCustomizations>
    
  2. Specify an Owner.

  3. Set the UseVoiceDomainForEmergencyCallBranding setting to one of the following values:

    ValueDescription

    0 or 'False'

    The OS inspects the registration state to decide the emergency call branding.

    This is the default OS behavior.

    1 or 'True'

    The voice domain decides the emergency call branding.

If `UseVoiceDomainForEmergencyCallBranding` is set to 1, the phone will not display **Emergency calls only** in the following cases. Instead, it will display **No service**.

-   If the system type ([RILSYSTEMTYPE](netvista.rilsystemtype)) is NONE, which means there is no signal.

-   If the system type is LTE but there is no voice domain. This situation can occur in these cases:

    -   In LTE networks being used by a non-VoLTE capable device without 3G coverage.

    -   In forbidden LTE networks.

However, if you do not set `UseVoiceDomainForEmergencyCallBranding` to 1, or the setting is missing, the device may display **Emergency calls only** in the above situations.

Testing steps:
Work with your mobile operator partner to test this customization on their network.

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