In my experience, it works only when there's usable LTE signal. For instance, if you initiated a call in LTE and walk to an area where LTE drops and the phone transitions to 4G/3G, the call would drop.
I would personally leave the feature off until your carrier completes migrating all the towers to LTE (T-Mobile expects to complete this sometime next year).Even where you can get VoLTE, you may have a frustrating experience with it, especially if you are a Verizon customer. If you initiate a VoLTE call on Verizon and then move to an area that has a tower that doesnt support VoLTE, the call will drop, company spokeswoman Heidi Flato said. For now, Verizon iPhone 6 and 6 Plus users have to manually turn on VoLTE by going into their settings.
Verizon's FAQ is usually a good resource for things of that nature: http://www.verizonwireless.com/support/faqs/WirelessService/AdvancedCalling.htmlI have a question....does using this feature count against your data? If so, why is this a good feature? Don't most of us have unlimited talking but limited data??
UPDATE: Never mind....the article answered my question. It doesn't count against your data....yet.
I believe Verizon's LTE rollout is complete at this point. The only times you should still get a 3G or 2G signal are: Very weak signal (different frequencies used for the different technologies may mean in some areas you can only pick up one of them,) when you're connecting to a picocell (Subways, large shipping malls, etc,) or when you're roaming onto another provider's network (your network identifier should change to "roaming" when this happens.)Verizon confirmed my finding:
I would personally leave the feature off until your carrier completes migrating all the towers to LTE (T-Mobile expects to complete this sometime next year).
Thanks for the resource! So from this document it seems to use it you have to give up Caller Name ID??Verizon's FAQ is usually a good resource for things of that nature: http://www.verizonwireless.com/support/faqs/WirelessService/AdvancedCalling.html