For Samsung phones, customers can activate/ deactivate VoLTE usage in 2 ways
1. Settings > Mobile networks > ON/OFF VoLTE Call
2. Access Notification Center (Swipe your finger from upper screen edge to lower direction) > Edit > ON/OFF VoLTE Call
For dtac Phone you will not turn off VoLTE usage unless you opt to 3G Network.

VDO call picture quality depends on your camera pixel and Frame Rate received from Network. However, both front and back cameras have the same pixel quality.

During ‘dtac 4G calling | VoLTE’ usage in VDO Call, if the phone captures 3G signal, the system will automatically switch from VDO Call to Voice Call as 3G does not support ‘dtac 4G calling | VoLTE’ usage.

During ‘dtac 4G calling | VoLTE’ usage in VDO Call, if the phone captures 2G signal, this will end the call as 2G does not support ‘dtac 4G calling | VoLTE’ usage and 2G Network is not able to switch to Voice Call. However this has lesser chance to happen.

Customers can use Voice Call uninterruptedly but for VDO Call usage, the system will automatically switch to Voice Call.

Customers will not able to continue as 2G Network does not support the usage.

Check the strength of 4G phone signal. If it is weak, we recommend you to switch to Voice Call usage instead.

Customers can change SIM and continue using ‘dtac 4G calling | VoLTE’ as usual.

Currently ‘dtac 4G calling | VoLTE’ does not support usage on secondary SIM (MultiSIM) yet.

None. Because all supporting phones (Samsung Galaxy S6, Samsung Galaxy S6 Edge and dtac Phone Eagle X) are automatically programmed to turn on VoLTE function automatically.

In the case of customers using unlimited internet and the speed is being reduced when reach FUP will still be able to use ‘dtac 4G calling | VoLTE’ for both VDO Call and Voice Call normally since use ‘dtac 4G calling | VoLTE’ does not use internet from package.

No, because ‘dtac 4G calling | VoLTE’ cannot connect to different service provider Networks due to their current inability to support VoLTE service.

Network switching only happens from 4G to 3G only of which customers can still use ‘dtac 4G calling | VoLTE’ Voice Call without being interrupted on 3G. After that even there is 4G signal in the usage range, the phone will not switch from 3G to 4G due to system’s limitation.

The disconnection will not be a problem but the audio quality of Voice HD will turn to normal Voice.

While using VDO Call on ‘dtac 4G calling | VoLTE’ and the device switches to 3G signal, the system will switch from VDO Call to Voice Call but you can still talk without interruption.

There will be no disconnection problem but VDO Call will switch to Voice Call when there is Network change from 4G to 3G but you can still talk without interruption. If there is a switch from 3G to 2G Network, customers will also not being affected and can carry on conversation as normal.

You cannot do it since during 3G conversation, the screen will not display 4G despite being in 4G Network coverage and you will continue conversation on 3G Network until hanging up. If you want to use ‘dtac 4G calling | VoLTE’ VDO Call or Voice Call, you must hang up and wait for the phone to capture 4G signal and then call again.

VDO Call will automatically be switched to Voice Call without notification.

Yes you can.
For Samsung phones, press button on to of the right side
For dtac phone Eagle X, press button and then choose “Voice Only”

If the receiving end is u on 4G and using dtac 4G calling | VoLTE service, they will be able to pick up your call and continue usage as usual.

Quality of dtac 4G calling | VoLTE usage depends on 4G signal strength.

We cannot determine the radius since signal strength depends on a number of factors and usage quality depends on captured signal on each phone.

Usage of ‘dtac 4G calling | VoLTE’ for VDO Call and Voice Call are charged per normal rates according to currently held packages.

dtac opens for usage from 15 October 2015 onward, customers can use ‘dtac 4G calling | VoLTE’ for free domestic calls during this introductory promotion period until 31 October 2015. International calls are charged per normal rates.

Usage of ‘dtac 4G calling | VoLTE’ for VDO Call and Voice Call are charged per normal rates according to currently held packages. There is no additional internet or service charges.

You can contact staffs at dtac service center of call 1678 dtac call center

Customers can dial to apply via *444*41*9#

If customers are using within dtac Network, customers will receive audio quality similar to HD Voice in 3G Network

Customers using ‘dtac 4G calling | VoLTE’ for VDO Call will get HD Voice quality as well.

HD Voice on ‘dtac 4G calling | VoLTE’ for either VDO Call or Voice Call has two times better quality and crisp audio.

We are testing it right now and will announce other phones that also work soonest.