All the carriers have wifi calling available. This will help in providing an HD Calling experience and also help avoid the dropped calls in homes or buildings where there is poor signal strength from the cell towers. I would recommend enabling this feature on your device as its a free service. Must be an LTE capable device.

for Android

  1. From a Home screen, navigate: Apps Apps icon > Settings.
    Note These instructions apply to Standard mode only.
  2. Tap Advanced Calling.
  3. Tap the Advanced Calling switch to turn on On indicator or off Off indicator.

 

for iphone

First, enabling LTE for voice & data

To enable HD Voice on your compatible iPhone:

  1. Tap Settings
  2. Tap Cellular
  3. Tap Enable LTE
  4. Tap Voice & Data

 

Then

go into settings, phone, then turn on wifi calling.