How to Check for Working 4G VoLTE Calling on Android Handsets
The Problems with VoLTE Interoperability & Standardisation
Table of Contents
- Introduction
- How to Check if 4G VoLTE Calling is Working
- Method 1: Phone Call Test (Easy)
- Method 2: IMS Status Check (Intermediate)
- Method 3: Phone Info — Call Type/Voice Network Type (Advanced) - VoLTE Icons
- Device Modem Configurations/Profiles
- Checking the device Modem Configuration/Network Profile - Further Information & Resources
- Sources & References
Relevant Articles
Introduction
The following guide outlines how to test for working VoLTE (Voice over LTE) aka ‘4G Calling’ on Android Devices. It also includes technical information that explains in some detail what is required to have working VoLTE Calling with a device, in addition to the issues that users may experience trying to enable calling on different devices and networks.
Background
While some people may be aware that 2G & 3G services will be gradually shut down in many regions this decade, the vast majority will be unaware that this may affect their ability to make or receive calls on their existing and in some cases brand new 4G & 5G devices.
4G/LTE and 5G technologies do not natively have voice calling functionality like 3G & GSM (2G) Services (‘Circuit Switched Calling’). 4G and 5G are Data only and Calling is enabled through the use of VoLTE (Voice over LTE or VoNR [New Radio] for 5G SA), which is a software/firmware VOIP (Voice over Internet Protocol) solution for mobile phones (IMS services).
Why this is a Problem
Unlike calling on 2G & 3G (GSM) there is no single configuration for 4G calling (VoLTE/IMS) that all devices and networks support.
Globally carriers can choose different settings to configure their VoLTE calling networks, and devices need to have explicit firmware support in order to have functioning calling. A device that supports VoLTE with one carrier network may not support VoLTE calling when on another network.
Compatibility Problems with 4G Calling
A significant number of 4G devices sold in previous years in various markets either are not enabled to use VoLTE Calling or ONLY support it with the Telcos/Carriers they were purchased with, regardless of whether the device is network unlocked. (Also affects imported devices, new & used).
This issue primarily impacts Android phones and non-Apple devices.
With 2G or 3G still being in service customers don’t experience any loss in device functionality by switching to a competing provider. However, without 2G/3G services people may no longer be able to make or receive standard phone calls on their existing 4G device with their preferred provider.
This also impacts Emergency Calls and Roaming Calls, not all devices with VoLTE Calling support can place Emergency Calls or Roaming Calls over 4G.
Apple Devices
Apple iPhone 6 (2014) and newer generally support VoLTE across the globe as Apple has complete control of the device software.
iPhone 5, 5s and 5C though 4G/LTE Phones Do Not Support VoLTE Calling.
Though VoLTE is better supported on iOS not all iPhones sold support the 4G Bands for every region in the world. (e.g. US Model iPhone XR, iPhone 11 lack LTE Band 28 [700Mhz] which is used in Australia, France, New Zealand etc).
Android Devices
Android is very fragmented from a software support side, however it’s fair to say that a majority of Android devices released around or before 2018 are likely to have either no VoLTE calling support or only limited VoLTE support on many networks (Depending on brand, firmware, region etc.)
Devices from Android 4 to Android 9 (2018) equates to approximately 27% of the Android Device Market as per Google’s stats from April 2023. It’s almost a certainty that anything Android 6/7 and older likely doesn’t have any support or at best, only support with one carrier in a given market.
Issues with 4G Call Roaming
Further to that, Optus (an AU telco) says VoLTE and VoLTE (International) Roaming should work on all Samsung Phones with Android 12 and above.
https://www.optus.com.au/mobile/plans/international-roaming/volte
Android 12 was only released in late 2021 so people who have Android phones older than 2020/2021 are likely to encounter issues with either switching providers or when travelling overseas.
Devices from Android 4 to 11 make up 69% of the Android Device Market as of April 2023.
Google made major changes to the base Android Operating system for Version 12. Those changes improved how IMS (IP Multimedia Subsystem) Services are activated and by extension VoLTE Calling and RCS Messaging etc. This is why Optus can say Samsung’s on Android 12 and above are supported.
Devices without VoLTE Roaming cannot make VoLTE calls when roaming on another 4G network. VoLTE Roaming uses the S8HR Architecture, this architecture routes the calls to the home mobile network.
Roaming devices that lack VoLTE Roaming support can use 2G or 3G Networks (if available) for making and receiving calls (via Circuit Switched Fallback). In countries without either 2G or 3G Networks, Roaming devices will not have access to call service from the connected Roaming Network.
Devices without VoLTE Roaming support may encounter issues placing Emergency Calls when Roaming on 4G.
How to Check if 4G VoLTE Calling is Working
Note: The below instructions do not test for 4G Emergency Calling Support. For (112/000/911) Emergency Calling testing instructions
See Here or Below (Very Advanced)🚨🚓🚑🚒
Method 1: Phone Call Test (Easy)
- On your 4G Device Pay attention to the Signal Indicator at the top of the screen, if it says 4G or LTE it means the device is connected to a 4G(LTE) Network for Data Services.
- Make a regular call via the Dialer (to another phone or voicemail) and watch the signal icon.
If it changes from 4G (or LTE) to a 2G/3G, E, H+ (or another non 4G/LTE symbol) then the device is likely using legacy (Circuit Switched) Fallback calling (CSFB) and not making a 4G call using VoLTE.
If the icon stays on 4G (or LTE) throughout the call then the device is likely using 4G(LTE) for calling and is VoLTE Compatible with your carrier network.
Note: When using legacy (CS) fallback calling the mobile connection to the whole device is downgraded to 3G (or 2G/GSM) in order to make that call.
This also means the mobile data connection is slowed down dramatically as well during the call. Once the call ends the connection is upgraded again.
Do note that the lack of a VoLTE icon whilst on ‘4G/LTE’ does not mean VoLTE isn’t enabled. (See below)
Important Note: Some Handset makers have re-badged ‘3.5G’ as ‘4G’, and LTE 4G shows up as ‘4G LTE’.
If an icon changes from ‘4G LTE’ to ‘4G’ it likely doesn’t support VoLTE.
See the Samsung Example below.
Method 2: IMS Status Check (Intermediate)
This Status Check method will vary depending on device model and firmware. (Android 7+) This method should work with most ‘stock-like’ Android ROMs like those used by Sony, Google, OnePlus, LineageOS etc.
There may be alternative approaches for other brands not listed in this guide.
- Open the Dialer and type the code *#*#4636#*#* to load the Phone Testing Menu
2. Wait for the Menu to load then Press ‘Phone Information’
3. On the ‘Phone Info’ Screen press the three dots located in the top right corner [ ⋮ ]
On this screen you can also see if VoLTE Calling, Video Calling and Wi-Fi Calling are ‘provisioned’ (enabled) within the Firmware (or build.prop) settings. VoLTE will not work if not provisioned.
Some device OEMs have a Secret Dialer Code that can ‘Force Enable’ the VoLTE setting on the device and make VoLTE ‘Provisioned’. However a carrier compatible modem firmware configuration is also required for VoLTE to work.
Examples of such Dialer Codes are below:
Asus Code : *#*#3642623344#*#* (Spells ‘ENHANCED4G’)
Xiaomi Code: *#*#86583#*#* (Spells ‘VoLTE’) & *#*#869434#*#* for VoWiFI
With some ‘stock-like’ Android Devices you can use the App ‘Pixel IMS’ to force on the VoLTE ‘Provisioned’ Flag and other settings. (incl. 5G One Plus, Xperia & Pixel Devices)
4. Select ‘IMS Service Status’
(Note: Devices running Android 7.0 or Older may not have ‘IMS Service Status’)
5. Check the IMS Status
(Note: This step does Not confirm working 4G Emergency Calling — See Here)
The other values are for WiFi-Calling (VoWiFi), Video Calling and UT Interface. If these say Unavailable then the feature is not working.
Note: To have WiFi Calling say ‘Available’ you need to be connected to a suitable WiFi Network and WiFi Calling has to be enabled in the Dialer/Phone Settings.
If UT Interface is Unavailable then you won’t be able to use the Phone Dialer settings to change carrier Call Forwarding or Call Busy Settings.
UT Interface isn’t required for VoLTE Calling.
UT Interface is only required to change supplementary service (i.e forwarding) settings on a 4G only network.
Blackberry
Follow the steps above but instead use the code *#*#46368676#*#*
Samsung (& Others)
Samsung Devices don’t support the *#*#4636#*#* (INFO) Debug code with OneUI 3.0 and newer. However ‘IMS Registration Status’ should be visible within the System ‘About Phone’ settings area.
Note: You can still launch the ‘Phone Info’ (com.android.settings.RadioInfo) interface on Samsung devices if you manually create an activity shortcut with something like Activity Launcher or similar. This may also work with other device brands that don’t support the native debug code.
Alternatively the code of *#77467# may display IMS Status on some older Samsung Devices (e.g S6, S7, S8, Note 9)
As an Alternative to the above, the App ‘NetMonster’ has a built-in shortcut for the ‘Phone Info’ Screen.
Method 3: Phone Info — Call Type/Voice Network Type (Advanced)
An alternative approach to the previous ‘IMS Status’ method is to check the Type of Call Connection within the Phone Info Screen during a call.
This requires opening up the *#*#4636#*#* Menu first (as above), making a call, then switching back to the ‘Phone Info’ App (via the App Switcher) with an active call and checking the results.
This approach can be used on devices that lack ‘IMS Status’ such as Samsung's & Xperia’s with Android 6 or 7 etc.
If the “Voice network Type” says ‘LTE’ whilst on a working call then VoLTE is working.
If the “Voice network Type” says ‘UMTS’ or ‘GSM’ then Legacy (non-VoLTE) Calling is in use.
Force ‘LTE Only’ Mode
As an optional (Advanced) step with this method you can set the preferred network type to ‘LTE Only’ instead of ‘LTE/UMTS auto (PRL)’.
By changing this setting it forces the phone to only connect over LTE (4G).
If calls don’t work on ‘LTE Only’ Mode then VoLTE isn’t working.
You may also need another App such as ‘Force LTE Only (4G/5G)’ to set the device to ‘LTE only’ on some newer devices (e.g. Phones on Android 11+).
Note: Before doing this please take note of the default preferred type and make sure to restore the setting after testing. Internet or Phone calls may not work properly if set to the wrong value. The device may need a restart or a ‘network settings reset’ via system settings to restore connectivity.
VoLTE Icons
If VoLTE is currently active, many devices will show a “VoLTE” (Voice over LTE/4G) icon at the top of the screen (near the signal indicator).
On some devices and in certain regions (e.g EU) you may see an “LTE” signal icon but this is NOT the same as “VoLTE”. LTE is an alternative technical name for ‘4G’ Data, VoLTE is a VoIP (Voice over IP) software feature/technology to enable calls.
Note: On many newer versions of Android device makers have removed a specific VoLTE icon being shown when VoLTE is enabled. Users may also see an ‘HD’ or ‘HD Voice’ during calls to indicate VoLTE, though HD Voice can operate without VoLTE so this isn’t a definitive indicator. You will need to have a “5G”, “4G” or “LTE” icon showing during calls to have working VoLTE.
Device Modem Configurations/Profiles
As mentioned earlier, in addition to a device having VoLTE enabled within the system settings (firmware and/or build.prop), the device must be running a modem configuration firmware/profile that is compatible with the network carrier. (The modem configurations are essentially advanced network settings for the device & modem.)
With VoLTE is there is no one standard/configuration that all 4G/LTE networks and devices universally support.
For VoLTE to work the device needs to have a compatible modem configuration available in the device firmware. (Depending on the Device & Network, Newer Android 12+ devices may be able to obtain working VoLTE via ‘TS.43 Service Entitlement Configuration’)
As an example see below tables of Qualcomm Modem configurations that were tested on Australian Networks. (Telstra, Optus and Vodafone AU, in addition to 000 ‘Triple Zero’ (112) 4G Emergency Calls)
For the tested devices to work on Telstra they must be running the Telstra Modem Configuration, devices running the GSMA ‘Open Market Device’ configuration/profile or a configuration from another carrier cannot get working VoLTE Calling on the Telstra network.
This limitation prevents Telstra customers from using ‘Open Market Devices’ which do not have native Firmware support for the Telstra Network.
Devices running an IR.92 ‘Open Market Device’ configuration can work on competing Australian networks Optus & Vodafone/TPG.*
For reference, the Snapdragon 820 Chipset (2016) was used in some of the following devices:
- Samsung Galaxy S7 & S7 Edge (USA)
- Sony Xperia XZ
- OnePlus 3
- LG G5
- Google Pixel 1 (Snapdragon 821)
- HTC 10
- HTC U Ultra (Snapdragon 821)
GSM Arena — Phone Finder — Snapdragon 820 + 821 Devices https://www.gsmarena.com/results.php3?sChipset=2,3
The Snapdragon 835 Chipset (2017) was used in some of the following devices:
- Samsung Galaxy S8 (USA & China)
- Samsung Galaxy Note 8 (USA & China)
- Sony Xperia XZ Premium
- Sony Xperia XZ1 & XZ1 Compact
- OnePlus 5 & 5T
- LG V30
- Google Pixel 2
- HTC U11 & U11+
GSMArena — Phone Finder — Snapdragon 835 Devices
https://www.gsmarena.com/results.php3?sChipset=1
Note: The test results noted with ‘NO — Call Fails’ are devices that support 4G Emergency calling in their respective home market or network, but Emergency Calls fail to connect on Australian 4G Networks even when 3G is available!
See the ‘Further Information & Resources’ section below for more information.
Checking the device Modem Configuration/Network Profile
With some OEMs/Devices you can check what Modem Configuration is currently loaded on the device. The various network (modem) configurations generally are preloaded with the device firmware by the manufacturer, this is still true with new devices (e.g Android 12+ [2021]).
With some devices the configurations are automatically loaded by the device firmware when inserting different sim cards. However not all devices sold or in use have the configuration files for every network and not all devices are configured to detect every type of network sim card and enable VoLTE Calling.
By default many devices will revert to a ‘non-VoLTE’ enabled Modem Configuration unless a ‘supported’ network sim card is inserted.
When a supported (carrier network) Sim Card is inserted into the phone the device will display a message that a restart is required to ‘optimise for your network operator’. The device will then restart and load the specific modem config and other software customisations for that carrier network.
With many newer 4G/5G devices, phones are frequently configured by default with a ‘ROW’ (Rest of World) or ‘ROW Commercial’ Modem Configuration .
The ‘ROW’ configurations on many devices are often a Generic ‘Open Market’ VoLTE Profile/Configuration. Devices with those configurations typically can have working VoLTE calling on networks that are ‘Open Market Device’ compatible. (Such as Optus and Vodafone AU etc.)*
In stark contrast, many US providers (such as AT&T) actually whitelist devices (IMEI TAC Detection). So even if the phone has the right firmware and hardware because it’s not an ‘approved’ device it’s blocked from connecting.
VoLTE support is also an existential problem for Custom ROMS and Open Source Phone Software, many Lineage OS ROMs can’t enable VoLTE unless it was already working with stock software.
VoLTE is also often implemented in a proprietary way that can’t be reversed engineered to enable support on custom Roms or Software. This is a common issue with many Exynos based Samsung devices.
Sony Devices
On Sony Devices you can check what modem config is currently loaded by using the dialer code to load the phone service menu.
Type *#*#7378423#*#* then wait for the SERVICE Menu.
Once loaded select “Service Info” then “Software Info” and at the bottom it will display the current Modem Config. (Android 9 example)
On Sony (Android 7.0+) Devices the OEM partition is what is customised by the Telcos. In many instances only one telco’s modem config is specified per firmware customisation. (e.g. Telstra AU, Optus AU, O2 UK etc)
The phone has all of the listed Qualcomm modem config files in the system partition however the OEM partition is responsible for telling the phone what one it should load.
(The ‘modem.conf’ file specifies the name of the mbn file to be loaded.)
The OEM partition also often contains things like pre-install apps, telco wallpapers, ringtones and boot-up animations etc.
Note: On newer Sony phones (sold with Android 10+) the mbn file system has been changed and should be the same across AOSP/OEMs (e.g mcfg_sw.mbn). The modem configs are instead stored within the modem firmware/partition in separate carrier folders rather than the system partition.
Features are indicated by the folder name (non_ims, vl, vlvw, vlvtvw etc)
vl = VoLTE, vw = VoWiFi (WiFi Calling), vt = Video Telephony/Calling.
Xiaomi Devices
With Xiaomi Devices there is an “MBN config loading and activating tool” that is built into the beta firmware builds of various Xiaomi Devices.
For more information see below.
Other Devices
With other Qualcomm based devices the use of software like ‘EFSTools’ and ‘QPST’ is necessary to check the current modem configuration.
These tools also offer options to change the configuration running on the device. However with some devices this requires root access to the firmware.
For MediaTek based devices the ‘MTK Engineering Mode’ Tool can be used.
Decompiled Modem Configurations — Examples
Nokia 8 — Telstra AU
https://github.com/JohnBel/QualcommMBNs/blob/master/extracted/mbn/Nokia/8/mcfg_sw/generic/aunz/telstra/commerci/mcfg_sw.mbn.json
OnePlus 3T — China Telecom — Open Market
https://github.com/JohnBel/QualcommMBNs/blob/master/extracted/mbn/OnePlus/3t/mcfg_sw/generic/china/ct/commerci/openmkt/mcfg_sw.mbn.json
Further Information & Resources
VoLTE Device Testing Information — Original Write-up — Nov 2023
Google Doc— ‘2G/3G Switch-Off & 4G VoLTE Calling Device Information’
4G Emergency Calling Testing Information — Original Write-up — Jul 2024
Google Doc — ‘2G/3G Switch-Off & 4G VoLTE Calling Device Information — Emergency Calling Testing’
Sources & References
What is a Circuit Switched Fallback (CSFB)?
https://ribboncommunications.com/company/get-help/glossary/csfb
Siretta — Circuit Switched vs Packet Switched Networks
https://web.archive.org/web/20231206141205/https://media.digikey.com/resources/siretta/siretta-circuit-switched-vs-packet-switched-networks.pdf
Doug Makishima, GSMA — ITU Workshop on “Voice and Video over LTE”
https://www.itu.int/en/ITU-T/Workshops-and-Seminars/conformity-interoperability/20150112/Documents/Abstracts%20and%20Presentations/S3P5_Doug_Makishima.pdf
GSMA New VoLTE Specification to remove Market Fragmentation (07/2016):
https://www.gsma.com/futurenetworks/digest/new-gsma-volte-specification-removes-market-fragmentation/
Annoyed that your phone won’t work on VoLTE or VoWIFI on other carriers? GSMA is working it:
https://ausdroid.net/news/2017/11/18/annoyed-phone-wont-work-volte-vowifi-carriers-gsma-theyre-working-answer/
GCF GSMA IR92 VoLTE Spec Presentation: https://www.globalcertificationforum.org/static/uploaded/c1683a68-b94c-4c75-a6470136dfed73a9.pdf
OptimERA- ‘VoLTE Emergency Calls — Testing of 3GPPCompliance in OEM Handsets’ — January 2020
https://optimerainc.com/wp-content/uploads/2021/11/OptimERA_VoLTE_Emergency_Calls_Report.pdf
EENA — Ensuring continuity of access to emergency services/VoLTE Standardisation Problem
https://eena.org/blog/webinars/volte-standardisation-problem/
The Potential Perils of 2G and 3G Switch Offs
https://eena.org/knowledge-hub/press-releases/the-potential-perils-of-2g-and-3g-switch-offs/
‘Should we stop the shutdown of 2G/3G to save lives??’ Rudolf van der Berg — Stratix — EENA 2022
https://drive.google.com/file/d/1WC16k8C1gpeFRJif23yDIuLSRg1OJOnZ/view
Operators expect ‘blood on the highway’ as US visitors lose 911 Access
https://www.capacitymedia.com/article/2a8jhlzsoucvynqade3up/news/operators-expect-blood-on-the-highway-as-us-visitors-lose-9-1-1-emergency-access
Additional Test Cases for IMS Emergency Calling — Wayne Cutler, GSMA
https://www.itu.int/cities/wp-content/uploads/2023/06/3_Wayne-Cuttler.pdf
Ofcom — ‘3G and 2G switch-off — Our expectations of mobile providers’ — 02/23 https://www.ofcom.org.uk/__data/assets/pdf_file/0025/252592/3G-and-2G-switch-off.pdf
Australia’s 3G Switch-Off — 2024
3G Switch-Off Could Stop Triple-Zero Calls | 10 News First — 17 March 2024
https://www.youtube.com/watch?v=iK98wI6d-W0
ABC — ‘Millions of Devices Caught out by 3G Shutdown’ — Jane Norman — 8 April 2024
https://www.abc.net.au/news/2024-04-08/million-iphone-android-devices-caught-out-3g-shutdown/103673864
ABC — ‘Telstra to Extend 3G Shutdown’ — Jane Norman — 6 May 2024
https://www.abc.net.au/news/2024-05-06/telstra-to-extend-3g-network-shutdown/103808110
Senate Estimates 30 May 2024 Video Stream — Department of Infrastructure
https://www.aph.gov.au/News_and_Events/Watch_Read_Listen/ParlView/video/2488638?startTime=04480 (Start 10:04)
https://www.aph.gov.au/News_and_Events/Watch_Read_Listen/ParlView/video/2488638?startTime=08118 (Start 11:05)
Shutdown of the 3G mobile network — Australian Parliament Senate Inquiry
https://www.aph.gov.au/Parliamentary_Business/Committees/Senate/Rural_and_Regional_Affairs_and_Transport/3GNetworkShutdown
Senate Inquiry — Shutdown of the 3G mobile network — Submission 32 — James Parker
https://drive.google.com/file/d/1wrwLDogtUCUn70GWY8yCsqbZvzZEvj2q/view?usp=sharing
Senate Inquiry — Shutdown of the 3G mobile network — Supplementary Submission 32 — James Parker
https://drive.google.com/file/d/1SNsWzH5rOWl62Wxe0I0dQbyDMvLQQcPm/view?usp=sharing
Rural & Regional Affairs & Transport — 3G Shutdown Senate Inquiry — 23/07/2024 — Public Hearing
https://www.youtube.com/live/Tlofv0UfoI0?t=7833s
Rural & Regional Affairs & Transport — 3G Shutdown Senate Inquiry — 24/07/2024 — Public Hearing
https://www.youtube.com/live/HvDvnfWTou0?t=355s
Rural and Regional Affairs and Transport References Committee — 23/07/2024 — Shutdown of the 3G mobile network — Hansard
https://www.aph.gov.au/Parliamentary_Business/Hansard/Hansard_Display?bid=committees/commsen/28167/&sid=0004
Quarterly reports from Telstra & Optus regarding 3G switch offs from 27 Mar 2023 to 27 Mar 2024
https://www.infrastructure.gov.au/sites/default/files/documents/foi-24-352--documents-for-release--pdf.pdf
https://www.infrastructure.gov.au/about-us/freedom-information/freedom-information-disclosure-log
Correspondence to, and responses from, the Minister for Communications relating to the shutdown of 3G networks between 27 March 2023 and 27 March 2024
https://www.infrastructure.gov.au/sites/default/files/documents/foi-24-354--documents-for-release--pdf.pdf
