Cell phone and internet access

[wrbird]

I have two ZE551ML ZenFone 2's. On one phone I can be on a call and access the internet at the same time (WiFi off). The other identical phone I cannot access the internet when I'm on the phone. I'm on T-Mobile and all the settings are the same.

Can anyone help me get this second phone fixed?

 

[B. Diddy]

Are both of them showing they have LTE reception? On the one that isn't working right, go to Settings>Cellular Networks, and look for an option for Enhanced 4G LTE, and make sure that's on. It might also be called VoLTE or Advanced Calling.

 

[wrbird]

Both phones do not have this setting, yet one phone works correctly and the other doesn't. I've attached a screenshot of the settings page.

Please let me know if you have any other ideas.

Is there any one else out there who can help?

 

[B. Diddy]

When you tap Preferred Network Type, what options do you get?