Will eventual USA 3G shutdown break current 4G phone voice calling?

December 26, 2018 9:24 AM

If 4G sends voice over 3G, what happens to 4g phone voice calling when 3G goes away?

I thought I had a good bead on this, but as it turns out, I don't. I'm technical but have paid little attention to cellular tech.

My question specifically regards 4G/LTE feature phones (i.e. flip or candy bar phones not running Android/iPhone/Blackberry), said phones running on US AT+T and T-Mobile MVNO's.

Smart phones, other carriers and 'visit your local cell phone store' are all out of scope. (For the benefit of future AskMe searchers: as of Dec 2018. Verizon is migrating to 100% LTE/VoLTE, and T-Mobile reportedly intends to do to Sprint what Sprint did to Nextel.)

Given that:
- Ordinary current 4G/LTE phones send voice calls over 3G and data over 4G/LTE.
- VoLTE will enable voice over 4G/LTE.
- Preference is to purchase any given phone unlocked and use as long as the hardware and network permit

My queston is two-fold:
- How will current 4G/LTE phones transmit voice calls when AT+T and T-Mobile eventually retire what each calls its "3G Network"? Will the phone go data-only?
- Pre-purchase, do I need to worry/how do I tell, whether an unlocked 4G feature phone will now or ever support VoLTE? Is VoLTE firmware-only or firmware plus hardware? Yes, I'm aware that vendors do not update firmware or add features indefinitely.

posted by zaixfeep to Technology (3 answers total)

VoLTE is voice over LTE. If device supports LTE, in theory a firmware update can enable VoLTE. Just like in theory you just need the client for VoIP (voice over IP) on your computer without needing to worry about the specific hardware. Of course if your hardware is way old, that's a different matter.

If a device does not support VoLTE, it will not be able to make a voice call once 3G network goes away. If you're simply worried about calls made from your house, there might be options - you can have micro cell in your home (which is unfortunately also being phased out) or if a device supports wifi calling.

I am not too familiar with flip phone sales and information provided but during certification the manufacturer has to state what technology a device will support. I'm fairly confident it's one of the information provided pre-purchase to consumers as well.
posted by 7life at 10:07 AM on December 26, 2018

Verizon likes to do things their own way, if you need a phone that supports volte with them, look through what phones they have that support volte. Since you went to buy it unlocked, if you don't buy it from Verizon you'll then have to find out from the internet if that exact model of 3rd party unlocked phone supports volte on Verizon, hint it may not since they like to limit 3rd party devices.

And expect a 3g voice & lte data device to stop working when 3g support is pulled.

My advice, since it's a feature phone, buy something cheap now with the foreknowledge that it's disposable and will stop working then buy a new one that works.
posted by TheAdamist at 12:46 PM on December 26, 2018

Thank you both for confirming what I suspected. I somehow missed the Wikipedia article "Voice over LTE" which currently sports a partial list of VoLTE-compatible phones. Amazon doesn't clearly confirm VoLTE in many phone descriptions, but the carrier websites' descriptions of the locked versions might. Also, 'HD Voice' capability appears to be an enhancement to and confirmation of VoLTE.
posted by zaixfeep at 1:12 PM on December 26, 2018