iPhone 6 and 6 Plus added a feature called LTE Voice (sometimes called HD Voice or VoLTE). LTE Voice uses the extra bandwidth available for LTE to make your calls super clear, if
- you are on a network that supports it (Verizon, AT&T, and T-Mobile, currently),
- you and the person on the other end are with the same provider (inter-network capability coming soon),
- you both have LTE Voice turned on with an LTE Voice-capable phone (many Android phones support it, too).
It isn’t turned on by default because the cellular providers are still working out the bugs in their networks, so you might be more likely to get dropped calls. Particularly with Verizon who doesn’t seem to have their network configured to allow calls to switch between LTE and 3G without dropping. Though Verizon customers may be attracted to the new ability to use data and voice simultaneously: no more having to hang up your phone before all of your messages come through.
To enable on your iPhone, go to Settings > Cellular > Enable LTE. Tap “Voice & Data”.
If you don’t see this option you may need to contact your carrier’s customer service. Verizon customers may need to add Advanced Calling to their plan through their account portal or by calling customer service.
A note for those with Verizon’s Samsung Network Extender: your phone will still make calls, but if you pick up any LTE signal at all, your phone will ignore the booster preferring the weak LTE signal. Since Verizon can’t transfer LTE calls to non-LTE, your phone will likely drop your call. If you drop calls a lot you may need to turn LTE Audio off.
Want to get HD quality phone calls but don’t meet the requirements to do a LTE Voice call? Two great alternatives are FaceTime Audio (FaceTime without the face part), or a Skype audio call.