Question Is VoLTE Really Needed? - Xiaomi Mi 11 Lite 5G

(US ATT and T-Mobile)
I have this phone, but only by way of ATT telling me my non-VoLTE 4G LTE phone would not work after ATT shuts down 3G.
I move over to T-mobile recently. All works ok. I then activate VoLTE on the Mi. All works ok.
But I had to call a T-mobile rep regarding my iPhone, in that conversation I asked if VoLTE was even needed, and he tells me no, that T-mobile will still do voice data w/o VoLTE enabled.
So, VoLTE is a feature of LTE and implemented on 4G/5G, and really has nothing to do with 3G being shut down.
There's so many sites stating you "need" VoLTE to keep making voice calls after 3G is gone. This is not true.
"As 3G is switched off, you need VoLTE or HD Voice support to make calls on 4G networks."
Explained: AT&T and T-Mobile VoLTE phone cutoffs
Everything you need to know about AT&T's move over to HD Voice and T-Mobile's transition to VoLTE, and what it means for smartphone calls.
www.androidauthority.com
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As I understand it you need 3G for voice.
You may be able to use internet service but without VoLTE, no phone service.
If the device is not white listed it likely will not be able to have phone service as your link states.

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I have straight talk with AT&T sim, I was using my Black Shark 3 pro which has volte and all of a sudden Friday at midnight, no data or phone service. At that time my bs3pro has been having heating issues, so i moved everything over to my redmagic 6 which has volte. I noticed my sim was locked in apn, totally different apn info than my bs3pro, so i called support, since everytime I tried to make call it blocked calls and sent me to support. The CS person did something on their end, had me restart phone, then service was back to normal and been fine since.

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If your service provider only provides 4G infrastructure like mine... then you need VoLTE otherwise no phone calls. They are new and never had any 3G and below infrastructure. I tried making calls .... it doesn't.
My service provider annoyingly doesn't provision volte for my volte capable handphone (this makes my eyes swivel) but does provide an app to support phone calls without volte.. but it chews up battery

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@roger_rex
But T-mobile (US) runs 4G and 5G, but # of towers with 5G not as plentiful as 4G. I connect 4G LTE most of the time, voice & data works just fine. T-mobile rep told me it will work w/ or w/o VoLTE enabled on phone. The APN used is the "fast" APN one.
A 5G connection does not negate any benefits from using VoLTE.

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Was on phone again today with a T-mobile "tech team supervisor" for a service issue (they accidentally turned off one of my SIM cards). I then asked about VoLTE, he tells me it's no longer needed on T-mobile 4G or 5G LTE, but using VoLTE will still work. He seemed to suggest VoLTE not needed at all on 5G because the speed of the wireless can carry both voice and data fast enough. He also hinted their 4G can do the same.
If you have a fast pipe then you really don't need a side channel for the voice.
But duly noted, everything technical that I have read about on VoLTE, using that feature gives better voice call on any LTE that supports VoLTE. The supervisor also mentioned that "VoLTE" will basically go away at some point.

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Pretty sure on 4G LTE you need either VoLTE capability or a 3G connection for voice calls.
Redirect Notice
4G VoLTE will likely be here for a long time as 5G is distance/obstacle limited, the former is very hard to overcome due to the wavelength's physical properties.

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@blackhawk
I am not disputing how online info says it's required, I am just copying what T-mobile has told me.
T-mobile store rep tells me VoLTE is not really needed, then their online support supervisor tells me the same thing. So it is for sure confusing.
Call a T-mobile support # and ask.
Why would a 3G/4G-LTE phone have an option to turn off VoLTE?
https://www.republicworld.com/technology-news/mobile/what-is-volte-and-what-it-does-is-5g-volte-know-everything-here.html

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ChuckStein123 said:
@blackhawk
I am not disputing how online info says it's required, I am just copying what T-mobile has told me.
T-mobile store rep tells me VoLTE is not really needed, then their online support supervisor tells me the same thing. So it is for sure confusing.
Call a T-mobile support # and ask.
Why would a 3G/4G-LTE phone have an option to turn off VoLTE?
https://www.republicworld.com/technology-news/mobile/what-is-volte-and-what-it-does-is-5g-volte-know-everything-here.html
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I never paid much attention to this and still have questions but it's back burnered for when I run across it. From what I'm reading the T-mobile reps sound like they don't understand it either.
Even if they don't understand it... the only thing that matters immediately is if it will work. Hopefully that intel is correct!
Really until AT&T implements the change I won't be 100% sure. However pretty sure I'm ok as the devices don't use the 3G band and in hidden user settings VoLTE is toggled on. The only indication other than the 4G that VoLTE is active.
Probably HD too, but no indicator or setting other than very good call quality.
To make matters even more confusing AT&T changed the format and models listed drastically 2 weeks ago from their December whitelist. So small wonder reps might be confused too. Makes you wonder if it was deliberately self serving, an oversight or ongoing system modifications?

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So, I have not been paying close enough attention to cellular these days. The cell companies have amassed large sets of licensed bands, probably near 200+ bands between 2G/3G/4G LTE and 5G NR.
Interestingly enough, 5G is not LTE at all. I suspect operators call their crud "5G LTE" to signify they support 5G-NSA or 5G-NR (or both), and, the older 4G LTE.
Some airlines are worried about two cell C bands (n77 and n79) that back up onto aircraft radio altimeter that run 4200-4400Mhz.
VoLTE has a long history, but it seems 5G-NR does not even use VoLTE (because VoLTE is a LTE feature, and 5G is not LTE). Can a 4G/5G phone still use VoLTE? Sure, if the firmware is implemented to use it. Likely will use it if the device connects 4G LTE, but perhaps will not when connected to 5G-NR. It's not clear to me if a device will use both 4G LTE and 5G-NR at the same time, but I suspect not. I mean, you could technically connect a device on 5G-NR for data, and then use VoLTE on 4G LTE for facilitating voice calls.
Some reference links for the interested reader.
5G Frequency Bands & Spectrum Allocations - CableFree
5th generation wireless systems, or 5G, may use existing 4G or newly specified 5G Frequency Bands to operate. Technologies include: Millimeter wave bands (26, 28, 38, and 60 GHz) are 5G Massive MIMO, "Low-band 5G" and "Mid-band 5G" use frequencies from 600 MHz to 6 GHz, especially 3.5-4.2 GHz.
www.cablefree.net
5G NR frequency bands - Wikipedia
en.wikipedia.org
LTE frequency bands - Wikipedia
en.wikipedia.org
List of LTE networks - Wikipedia
en.wikipedia.org
Voice over LTE - Wikipedia
en.wikipedia.org
What is 5G LTE, NR, NSA, and MIMO Technology | How Will 5G RAN be Deployed? | Corning
Learn about 5G deployment including RAN, 5G-NSA, 5G-NR, and what they mean for LTE networks.
www.corning.com
LTE vs NR: Reference signal design
NR downlink reference signals are tailored for specific roles and can be flexibly adapted for different deployment scenarios and spectrum. 5G Training
www.5gworldpro.com

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ChuckStein123 said:
@roger_rex
But T-mobile (US) runs 4G and 5G, but # of towers with 5G not as plentiful as 4G. I connect 4G LTE most of the time, voice & data works just fine. T-mobile rep told me it will work w/ or w/o VoLTE enabled on phone. The APN used is the "fast" APN one.
A 5G connection does not negate any benefits from using VoLTE.
Click to expand...
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My understanding on this is that voice was using some 3G or below service. My provider was purely 4G and above - so unless my phone was provisioned by the cell company - no voice calls. I tried & it didn't work. I changed to an older device that they did support via VoLTE and calls worked. I can download an App from the cell company that allows my pixel 2XL to work on their system.
I can only guess T-mobile has 3G and below network infrastructure still. My provider is brand new and never built any 3G stuff and have no intention of rolling out obsolete stuff. VoLTE is annoying in that the provider gets to pick and choose which cellphones they allow (to use a standard protocol)
This may not be 100% - I've been kind of forced into a crash course on this myself over the last few days

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@roger_rex - Take a read here
{Guide} QXDM Port activation on Pixel 2 XL, (VoLTE,WoWIFI,CA)
Hi all. First of all I DO NOT PROVIDE ANY KIND OF SUPPORT. YOU ALONE RESPONSIBLE FOR ANY POSSIBLE ISSUES. I wrote this post during my vacation. I know it could be quite handy, but unfortunately/thankfully my primary sources of money are...
forum.xda-developers.com
Pixel 2's all have ability for VoLTE.
A cell operator should not be blocking any phone from using VoLTE.
When you call your provider what do they tell you when you tell them your Pixel 2 has VoLTE for 4GLTE but your Pixel won't make calls on their network?

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I can tell you for sure, the operators play games with their support of hardware.
My iphone XS was connecting to ATT with a "5G" icon from time to time, so why does T-mobile say 5G is a "no"? I moved the XS to T-mobile and the phone won't ever connect to 5G, and the APN settings appear to be blocked.
Tutorials | T-Mobile Support
Update: I find many sites that say the Xr and Xs do not support 5G, so now I scratch my head, my Xs would sometimes show "5G" icon for cell wireless, when it was on ATT network. Apparently AT&T supports Xs and 5G, hence the Xs does have 5G capable radio.
Apple iPhone Xs / Xs Max - Signal & Cellular Data - AT&T
Get Apple iPhone Xs / Xs Max support for the topic: Signal & Cellular Data. Find more step-by-step device tutorials on att.com.
www.att.com

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ChuckStein123 said:
I can tell you for sure, the operators play games with their support of hardware.
My iphone XS was connecting to ATT with a "5G" icon from time to time, so why does T-mobile say 5G is a "no"? I moved the XS to T-mobile and the phone won't ever connect to 5G, and the APN settings appear to be blocked.
Tutorials | T-Mobile Support
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I think they go at least partially by number of a given model in use. My guess is it's not a painless procedure for them to configure their system for a given model.
AT&T first listed their Note 10+ variant but not the unlocked variant, a month later it was added as well. It may be a work in progress... it seems sort of helter skelter, oh my gawd get it done, whatever it takes... kind of deal
You know they are catching Berlin air raid volume flack

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Before buying Mi 11 Lite 5G I went into a T-mobile store (not an affiliate). I asked if the Mi 11 Lite 5G will work on T-mobile and the rep told me all phones work on T-mobile as long as they are not locked to another carrier, and, the T-mobile freq bands ("channels") are covered by the phone.
Unless LTE or 5G-NR/5G-NSA is improperly implemented on the device, then I don't see why all phones should not work. They should all work.
Think about hotspot. The carrier can control is the device can use that service, or at least can with some devices, but why bother, who cares how the data on the data plan gets chewed up. Go over the plan and get charged. Thus far I have not seen unlimited hotspot data, T-mobile only allows 40G on their Magenta Max plan.
Good thing is, Mi 11 Lite 5G phone (model M2101K9G) works a-ok on T-Mobile USA. I did have to manually set the APN to the "fast" one, and had to use dial code for VoLTE, 4GLTE and 5G works.

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Straight talk now keeps shutting off my service every 3 days, last night again, so 3 times now. Call and back working. But seems like they only care about giving me some crappy free phone and seems like they outsource. The redmagic 6 is not on AT&T list, if any more issues I will switch to T Mobile, T Mobile recognized my phone by imei and said it is fully compatible. I Noticed on my Redmagic 6, sim 1 is only 14 digits but sim 2 is 15, so I moved sim card, might be issue, but doubt it.

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@Rotwiler I see you posted about the IMEI digit thing in another post/forum. *#06# should reveal a 15 digit IMEI. If it shows only 14 then the phone is hiding one digit. Put sim card in sim slot that has the 15 digit IMEI.
What does *#*#4636#*#* get you? Do some gooling around for activating VoLTE on RedMagic 6
Phone lists for carriers are mostly for support reasons. If the phone has all the cell bands the operator uses, then it should be good to go. If the phone only has some of the cell bands used, then the phone may work ok in one area, but not good in another, all depends on how the operator runs the bands in different areas. The cell operator does not want the support headache for a phone that only has partial bands, "hey ATT, my phone not working in Timbuck-too", etc.
The RM6 appears to have most of the ATT 4GLTE bands (all the major ones), so it should work a-ok on ATT (US). 5G should also work. It appears the RM6 had a firmware update about 26d ago. Make sure the firmware is updated to latest.
Are your APN settings correct?
Program Data Settings for Your Device
Can’t connect to the internet on your mobile device? Here’s how to set up the access point name (APN) to get you going again.
www.att.com

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I am using AT&T through Straight Talk. I did move sim card to slot 2 to see if issue was due to sim one showing only 14 digits. Phone is fully updated. Odd thing is I cannot change the APN since this new Volte, there is red check mark and everything is grayed out. I have always been able to modify APN until now. My sim card is really old, used to be full size and over the years cut it down for new phones, is probably 8+ years old, had it since Android phones came out, but has always worked great.

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Rotwiler said:
I am using AT&T through Straight Talk. I did move sim card to slot 2 to see if issue was due to sim one showing only 14 digits. Phone is fully updated. Odd thing is I cannot change the APN since this new Volte, there is red check mark and everything is grayed out. I have always been able to modify APN until now. My sim card is really old, used to be full size and over the years cut it down for new phones, is probably 8+ years old, had it since Android phones came out, but has always worked great.
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APN settings are grayed out when the phone is locked to carrier. Can you at least see what the APN settings are? If the phone is owned outright by you then tell the Straight Talk folks you want the phone unlocked.
As for old sim card, then just go get a new one from the store for a few $, and then move your number to the new sim card via online.

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Phone is Redmagic 6 global version, never was locked.