Editing Voice over LTE (section)

==Issues with device compatibility==
VoLTE has been supported with Qualcomm Snapdragon Chipsets since at least 2013/2014 (e.g., Snapdragon 800/801), but not all Android devices that have been sold have VoLTE enabled by the manufacturer.<ref>"[https://www.qualcomm.com/products/mobile/snapdragon/smartphones/snapdragon-8-series-mobile-platforms/snapdragon-processors-800 Snapdragon 800 Processor]". ''Qualcomm''. Retrieved 8 August 2024.</ref><ref>"[https://www.qualcomm.com/news/releases/2014/07/qualcomm-announces-first-large-scale-commercial-volte-launch-japan Qualcomm Announces First Large-Scale Commercial VoLTE Launch in Japan]". ''Qualcomm''. 8 July 2014. Retrieved 8 August 2024.</ref> In many instances, devices will also lack the correct carrier network configurations/profiles to support VoLTE calling on all networks.<ref>"[https://www.gsma.com/newsroom/article/new-gsma-volte-specification-removes-market-fragmentation/ New GSMA VoLTE Specification Removes Market Fragmentation]". ''GSMA''. 28 July 2016. Retrieved 8 August 2024.</ref>

Unlike calling with 2G and 3G, there is no single configuration for VoLTE that all devices and networks universally support. Some networks support the GSMA IR.92 'Open Market Device' Configuration.<ref name=":1">Parker, James (31 August 2024). "[https://medium.com/@jamesdwho/how-to-check-for-working-volte-calling-on-android-8c343362ecfe How to Check for Working 4G VoLTE Calling on Android Handsets | The Problems with VoLTE Interoperability & Standardisation]". ''Medium.com''. Retrieved 2 September 2024.</ref> This configuration is intended as a generic/global VoLTE configuration that can be used by Open Market (non-carrier) devices.<ref>Doug Makishima, GSMA (1 December 2015). [https://www.itu.int/en/ITU-T/Workshops-and-Seminars/conformity-interoperability/20150112/Documents/Abstracts%20and%20Presentations/S3P5_Doug_Makishima.pdf "ITU Workshop on "Voice and Video over LTE""] (PDF). ''ITU''.</ref> 4G/LTE Devices that lack native VoLTE calling support are reliant on 2G/3G Networks to make or receive calls (via Circuit Switched Fallback - CSFB). Without either 2G or 3G Networks, those devices do not have call service.

A device may be marketed as having VoLTE support. However, the device may only make calls on some networks due to varying network configurations and VoLTE standardization issues.<ref name="EENA2022">[https://www.youtube.com/watch?v=sHjyLmFt-eg "EENA 2022: Access to emergency services is being impacted by the lack of VoLTE interoperability"]. ''YouTube''. 31 May 2022. Retrieved 7 August 2024.</ref>

In some instances, the retail versions of devices have been sold without VoLTE Calling on any networks (depending on brand/market/region). However, the exact same device purchased directly from a carrier (with carrier software) will support VoLTE on that carrier network.<ref name="HughVoLTE">Hugh Jeffreys (26 November 2023). [https://www.youtube.com/watch?v=Q6qb9dml6So "Carriers are Killing 4G & 3G Devices - Your 4G Phone May Soon Stop Working"]. ''YouTube''.</ref><ref>[https://www.youtube.com/watch?v=RPlTz-3estM "Australia Blocked Internationally Purchased 4G/5G Phones As Part of 3G Shutdown - Starting 28th Oct"] - 29 September 2024 - Youtube.com - Hugh Jeffreys</ref> Equally, some handsets purchased from another carrier or from another market may not be configured (in software) to support VoLTE on all networks within a given country. This issue primarily affects Android Phones and non-Apple devices. The iPhone 6 (2014) with iOS 10 and other newer devices support VoLTE calling on most networks. On the iPhone 5 and 5s, though, 4G/LTE devices do not support VoLTE calling.<ref>[https://support.apple.com/en-us/111954 "iPhone 6 - Technical Specifications"]. ''apple.com''. Retrieved 8 August 2024.</ref><ref>[https://www.telstra.com.au/support/mobiles-devices/enable-volte-mobile-phone "How do I enable VoLTE on my mobile phone?"]. ''Telstra''. Retrieved 8 August 2024.</ref><ref>[https://assistance-1.free.fr/mobile/terminaux/ "Free France - Mobile Phone Compatibility - VoLTE"]. free.fr</ref>

For example, for an Android device to have VoLTE Calling on the [[Telstra]] network, the device must run a [[Telstra]] Modem Configuration. Devices that run the GSMA 'Open Market Device' configuration or another carrier's configuration 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. Open Market configuration devices can work on competing Australian providers Optus & Vodafone.<ref name=":1">Parker, James (31 August 2024). "[https://medium.com/@jamesdwho/how-to-check-for-working-volte-calling-on-android-8c343362ecfe How to Check for Working 4G VoLTE Calling on Android Handsets | The Problems with VoLTE Interoperability & Standardisation]". ''Medium.com''. Retrieved 2 September 2024.</ref><ref name="HughVoLTE">Hugh Jeffreys (26 November 2023). [https://www.youtube.com/watch?v=Q6qb9dml6So "Carriers are Killing 4G & 3G Devices - Your 4G Phone May Soon Stop Working"]. ''YouTube''.</ref>

With some Qualcomm based Android devices, it is possible to modify the device firmware with special software and then manually load a compatible carrier modem configuration.<ref name=":1">Parker, James (31 August 2024). "[https://medium.com/@jamesdwho/how-to-check-for-working-volte-calling-on-android-8c343362ecfe How to Check for Working 4G VoLTE Calling on Android Handsets | The Problems with VoLTE Interoperability & Standardisation]". ''Medium.com''. Retrieved 2 September 2024.</ref> By modifying the firmware, customers can use VoLTE calling; however, the carrier may not recognize those devices as supported despite working correctly.

For example, starting in May 2024, Telstra started forcing a pre-recorded message with all outbound calls advising affected customers to upgrade in advance of the 3G shutdown in August. However, even customers with modified and working VoLTE devices on Telstra were hearing the message every time they made a 4G VoLTE call.<ref>[https://reddit.com/r/oneplus/comments/1aebdxz/unlock_volte_in_australia_oneplus_5_6_7_8_9/ "Unlock VoLTE in Australia Oneplus 5, 6, 7, 8, 9"]. ''Reddit''. 30 January 2024. Retrieved 8 August 2024.</ref> This is due to Telstra relying on established lists of 'compatible' devices they sold (i.e. Device IMEI/TAC codes).<ref>[https://www.youtube.com/watch?v=zIJavqEzEIw "Australia’s New Firewall IMEI BLOCKED 516,875 Active Phones Overnight + Tourists Phones Blocked"] - youtube.com - Hugh Jeffreys - 10 Nov 2024</ref>
[[File:Android IMS Status for Voice over LTE.jpg|thumb|280x280px|Android IMS Status for Voice over LTE]]
Android users are able to confirm if VoLTE is working by checking for the Device 'IMS Status' within a hidden Radio Info Debug menu.<ref name=":1">Parker, James (31 August 2024). "[https://medium.com/@jamesdwho/how-to-check-for-working-volte-calling-on-android-8c343362ecfe How to Check for Working 4G VoLTE Calling on Android Handsets | The Problems with VoLTE Interoperability & Standardisation]". ''Medium.com''. Retrieved 2 September 2024.</ref><ref>[https://www.androidpolice.com/best-secret-codes-for-android/ "The best secret short codes for your Android phone"]. ''Android Police''. 27 June 2024.</ref>

If the IMS Status shows "'''IMS Registration: Registered'''" and "'''Voice over LTE: Available'''" then VoLTE is enabled and working. An IMS Status of "'''Not Registered'''" and "'''Voice over LTE: Unavailable'''" indicates VoLTE is not enabled or working. However, the IMS Status debug '''does not''' confirm working 4G Emergency Calling support.<ref name=":0">Parker, James (1 September 2024). [https://medium.com/@jamesdwho/the-little-known-problems-with-volte-emergency-calling-3d4cdaf0e042 "The Little Known Problems with VoLTE Emergency Calling | How to Test for 4G Emergency Calling Support on Android"]. ''Medium.com''. Retrieved 2 September 2024.</ref>

For VoLTE calling to be "Available" on a device, VoLTE has to be both provisioned/enabled in the Firmware, and a carrier compatible modem configuration/profile must be loaded on the device. Typically, the modem configurations are automatically loaded by the device firmware when inserting a sim card. However, not all devices are configured to detect the sim cards for all networks and enable VoLTE Calling.<ref name=":1">Parker, James (31 August 2024). "[https://medium.com/@jamesdwho/how-to-check-for-working-volte-calling-on-android-8c343362ecfe How to Check for Working 4G VoLTE Calling on Android Handsets | The Problems with VoLTE Interoperability & Standardisation]". ''Medium.com''. Retrieved 2 September 2024.</ref>

The IMS Status debug can also indicate if Wi-Fi Calling (Voice over Wi-Fi) and Video Calling (VoLTE/Video Telephony) are available. 

''(Note: For Wi-Fi Calling to say Available, the device has to be connected to a suitable Wi-Fi Network).''

Additionally, devices with a "UT Interface" status of "Unavailable" will be unable to change Call Forwarding or Call Busy Settings over 4G/LTE. 

''Note: UT Interface is not required for VoLTE Calling. UT Interface is only required to change supplementary service settings (i.e. call forwarding) on a 4G/LTE only network. Devices without an "Available" UT Interface are reliant on 2G/3G networks to change call forwarding/busy settings.''