VoLTE - what is it on the phone, how to enable and disable it

VoLTE - a new type of communication

Most 4G wireless networks today use the LTE network. Outdated 2G and 3G networks were mainly intended for transmitting voice calls. Cellular data support was later added. The modern network allows you to transfer data at high speeds of up to 45 Mbit/s. But often the speed is much lower, since its parameters are influenced by many factors, for example, the distance between the phone and the base station.

VoLTE technology transmits voice messages over the LTE network. It first appeared on SingTel. Soon after, Samsung released the first smartphones with VoLTE service. The improved form of communication was quickly appreciated by mobile phone manufacturers and telecom operators. The enabled option significantly reduces the network load. The conversation between the interlocutors occurs without interference, with good sound quality.

4G communications with VoLTE technology have been used by subscribers all over the world, including in Russia, since 2021. Users appreciate high-speed Internet on their phones using the services of well-known operators.

What is Vo LTE

Development of new wireless communication technology began back in 2014. Moreover, the first smartphones on which the LTE network was tested were Samsung. The transition to the new regime has already taken 4 years and the process is not completed. Distribution problems are associated with the complex infrastructure that is required for the system to fully operate. For example, in Russia, not all regions support 4G networks, especially those in the central, densely populated territory. But development work continues, and in the coming years there will be dense coverage with new networks.

Smartphone owners are alarmed by the appearance of unfamiliar inscriptions on the display. The question arises - what does the icon on a Vo LTE phone mean? Here are the main definitions of the service:

Translated from English, Voice over LTE means “Voice over LTE”. 4G is presented as a technology for receiving and transmitting Internet signals, while the potential of the technology is broader. Vo LTE transmits voice messages over a high-speed LTE network

Compared to previous transmission methods via 3G or even 2G, Vo LTE has greater capacity and also provides greater signal throughput. It is not only important that the smartphone supports Vo LTE, it is also necessary that the operator provides a similar tariff. For example, there are still no suitable offers in Biline.

For audio transmission, IP Multimedia Subsystem (IMS) technology is used, that is, the IP protocol is used for operation.

Brief information about the development and implementation of technology

4G/LTE technology, which provides greater capacity, has been developed since 2000 and implemented since 2010. The first commercial LTE network was put into general use by the Swedish company TeliaSonera in 2009. This event debuted in Stockholm and Oslo. For now, the communication protocols used for LTE are limited to IPv4. In addition, there is a transition to a more secure IPv6, which allows you to increase communication speed.

Research is currently underway into the relatively simple operation of OFDM (Orthogonal Frequency Division Multiplexing) technology. To ensure the fastest possible data transfer, special antennas are used - N, as well as M. Antennas N transmit data, and M antennas receive it. This technology is called MIMO.

The meaning of the design is as follows: with the correct location of the antennas, a weak correlation between neighboring ones is achieved.

Few people knew what VoLTE was in a phone, but now it is a world-famous and widely used advanced communication technology. VoLTE translates to “voice over long-term evolution.” In other words, voice over LTE. Excellent sound quality during negotiations is achieved thanks to HD Voice codecs. With such calls, the sound range increases by almost 4000 Hz! In addition, the station serving subscribers can withstand a load three times greater than the previous ones. It turns out that the capacity of the mobile network increases by the same amount.

VoLTE - what is it in a smartphone?

Most people know that they connect to the mobile Internet through 2G, 3G, 4G networks. But not all subscribers are aware that voice calls are also made through them.

It is important to understand that all mobile network standards differ in bandwidth. This fact affects the quality of voice transmission when making calls. Naturally, if 2G networks are used, the operator has to compress the signal to ensure a stable connection.

For years, companies transmitted signals primarily over 3G networks. They provide good call quality, but in practice the sound is far from perfect. Now operators are starting to gradually introduce calls over 4G networks, and MTS was one of the first.

VoLTE Geography

The "Big Four" Russian mobile operators - MegaFon, MTS, Beeline and Tele2 - have already begun to support VoLTE, but not in all regions of Russia and not for all smartphones, even with technological support. Basically, VoLTE now works only in Moscow, the Moscow region, St. Petersburg and the Leningrad region, in the 4G coverage area. A complete list of devices and regions that work with VoLTE for a specific carrier can be found on its official website or customer support.

Flaws

• It is still common to find smartphones that do not support VoLTE. Most popular manufacturers have added it to new smartphone models, but not all.
• You won’t be able to use the technology if your current device doesn’t support it, and there are no plans to change your phone in the near future.
• VoLTE only works on 4G networks. In Russia, 4G coverage is not available everywhere, and if it is not available, the call will go through the regular network.
• At the same time, the mobile operator must also support VoLTE in the region where the subscriber is located, otherwise this function on the phone is useless.
• Although the sound quality is significantly improved when using VoLTE even for one of the interlocutors, ideal communication can only be achieved if both subscribers use it.

Why it's useful

VoLTE is highly appreciated by leading smartphone manufacturers, especially mobile operators, including Russian ones. Using this technology can significantly reduce the load on the network. But what does this setup offer the average subscriber?

• When calling via VoLTE, gigabytes of the Internet package are not consumed, only minutes. Despite the fact that the call takes place over 4G, operators consider this a regular telephone conversation and not an Internet call. This is especially useful when traveling abroad: high-quality voice communication that does not consume gigabytes.
• It takes about two seconds for a regular phone to switch from mobile internet to GSM - this is the time you have to wait to make a call before connecting. VoLTE eliminates this delay.
• VoLTE subscribers report better audibility than when calling over GSM/3G, even if the other person's device does not support this technology. Delays and interruptions during calls have been eliminated, as is the case with voice calls via WhatsApp and other mobile applications.
• Save battery power. VoLTE calls consume slightly less power than GSM due to the DRX mode. DRX means your phone will receive a signal at intervals when you make a voice call. Interruptions do not affect the quality of communication, but save battery power, since the antenna is turned off at this time.
• For a normal phone call, you cannot use 4G Internet as the device switches to GSM or 3G network when making a call. Sometimes the mobile Internet turns off completely. VoLTE allows you to simultaneously talk on the phone and surf the Internet at high speed.

Advantages and disadvantages of VoLTE

Advantages:

1. There is no need for automatic transfer from 4G to 3G. Basically, smartphones are in 4G mode, if you are in the coverage area, of course. When making a call, the smartphone switches from 4G to 3G mode, which takes some time. If VoLTE is enabled, the smartphone remains in 4G mode - there is no need to switch to anything.
2. The quality of received and transmitted sound improves - with VoLTE everything will be clear and clean. True, if you already had excellent sound quality, then you may not really notice the difference. It is also necessary to note the fact that the sound quality will remain the same if the subscriber you are calling makes voice calls over a 3G network.
3. 4G Internet will continue to work during voice calls. If you want to use the Internet simultaneously with an established voice connection, that is, talk on the phone and surf the Internet or download something from there, both types of connections require the same network. In our case it will be 4G LTE. A less advanced option is also acceptable - both voice and Internet via 3G. If you have 4G Internet and a 3G voice connection, then when you make an outgoing call or receive an incoming call, the smartphone will switch to 3G mode, which will block Internet access until the call ends. This can be especially unpleasant when making calls via WhatsApp and other applications - any call interrupts the voice Internet conversation. This will not happen with VoLTE.

Flaws:

1. Setup. It all depends on the smartphone and mobile operator. For example, to begin with, I had to unlock the VoLTE mode, since it is initially blocked on Xiaomi (you can read about how to unlock VoLTE on Xiaomi in a separate article), then enable VoLTE in the settings and connect, which provides access to technologies VoLTE and Wi-Fi Calling. And, for example, for a friend of mine with a Samsung smartphone and the Beeline mobile operator, VoLTE, after Beeline began supporting it, connected and started working automatically.
2. A number of conditions. The subscriber must have LTE support on the smartphone, VoLTE support with firmware that is suitable for working in Russia, the subscriber must be in a 4G operating area, his home region and the region in which he is located must support VoLTE technology (depending on the mobile operator).

Controversial points and additional information:

1. Battery consumption. When the 4G signal is weak, VoLTE calls may use more power to maintain the radio signal. But the difference in costs for an ordinary subscriber who does not talk on the phone 24/7 will be absolutely unnoticeable.
2. VoLTE does not consume mobile Internet. Calls, although they are carried out over LTE, are considered voice calls, therefore standard call tariffs apply - a package of minutes is spent or money is charged for minutes of conversation (in tariffs without a package of minutes or after the package of minutes ends).

Advantages and disadvantages of VO LTE2

VO LTE2 calling technology has both advantages and disadvantages. And after analyzing them, you will understand whether you need it or whether it is better to turn it off.

Let's look at the advantages first:

• To make a VO LTE2 call, you do not need to make special calls - the call is made in the traditional way. The main thing is that the smartphone supports this function, that it is turned on and that you are within reach of this technology.
• On VO LTE2 the call is made a few seconds faster. This is because the smartphone does not need to switch from 4G data mode (which is the default for most modern smartphones) to 3G mode. Surely everyone has encountered the fact that after dialing a number you need to wait a few seconds before the beeps sound. In the case of VOLTE, the situation is different.
• If you downloaded or transferred some large files via 4G, and then they called you, the phone will switch to 3G mode, accordingly, 4G mode is turned off and file transfer stops. In most cases, you will have to start over again after the call, which can recoup the paid traffic spent. But during a VO LTE call, the 4G transmission will not be interrupted, and the Internet will work even during a call.
• Despite the high quality, the cost of a call using this technology will not be higher than that of a regular call on the 3G network. In this case, a VO LTE2 call is made to Internet resources via 4G, but in most cases there is no charge for traffic. Regular call minutes will be deleted.
• The main advantage of this technology is the ability to talk to several people at the same time.
• VOLTE is supported by all Russian operators, but not yet in all regions. But the second is already a disadvantage.
• The main advantage is better sound quality. There will be no unnecessary interference or noise in the conversation; you will hear your interlocutor as clearly as if he were nearby.

Among the disadvantages of the technology, the following can be canceled:

• When making a call via VO LTE, the load on the smartphone increases and therefore the battery drains faster. But it will only be delicate when there is a lot of conversation. Just a few minutes of conversation a day and you won't feel the difference.
• If you call from a device that supports VO LTE2 to a device without this support, the sound quality will be the same as for 3G.
• To use this technology, it must be supported by the smartphone, which is not yet the case for budget models.
• If 4G in your area is unstable, it is better not to enable this option. Because if the 4G Internet signal disappears during a call, the call will be interrupted and you will have to call again.
• As mentioned above, this is not everywhere yet. But every year the coverage area is increasing, and soon VO LTE2 will be available in many regions.

Advantages and disadvantages of the standard

Although VoLTE technology is still in its development stage at the moment, its advantages are quite obvious. These include:

• Higher connection speeds achieved by eliminating the need to switch your mobile device to GSM or 3G when making a call.
• Higher voice quality. The data transmission speed in 2G and 3G networks is limited, which does not allow the transmission of voice modulation components in full. The throughput of LTE is much higher, more voice data is transmitted through such a network, and the use of HD Voice codecs gives volume to the sound and reduces the amount of noise.
• With VoLTE, simultaneous transmission of voice and other data is possible. In 2G and 3G networks, when making calls, the transmission of Internet traffic was usually temporarily suspended. This is due to the fact that with the simultaneous transmission of voice and other data, the quality of communication sharply decreased, while the load on the network, on the contrary, increased. VoLTE does not have these restrictions.
• Increasing the capacity of cellular networks. The use of VoLTE technology allows you to increase the number of simultaneously using communications subscribers up to three times compared to 3G without significantly increasing the load on the network.
• Free calls. Since voice is transmitted in packet mode when using VoLTE, only Internet traffic is consumed. If the user is connected to an unlimited tariff, all calls he makes can be considered practically free.
• Save battery power. The VoLTE standard provides a special DRX mode, which ensures reception of a base station signal with short interruptions. During such breaks, the device's radio is turned off, therefore, battery consumption is reduced.

These were the main advantages of VoLTE. On the other hand, it has its own number of disadvantages, due to which users often abandon the new technology. At the moment, the main disadvantages include:

• Increased demands on the hardware resources of a mobile phone. The VoLTE operating algorithm must be implemented at the processor level; if the requirements do not meet, the load on the mobile device may increase.
• Limited number of phone models supporting VoLTE. The new technology is supported only by the latest models of mobile devices.
• To ensure the stated sound quality, VoLTE must be used by both the caller and the recipient of the call.
• Difficulties in transition to a new standard by mobile operators. It will be possible to take advantage of VoLTE only after all operators decide to make the standard the main one.
• VoLTE is not supported by all operators or in all regions due to the lack of appropriate equipment on the towers.
• Vulnerabilities in VoLTE technology.
• The standard may not be available in intranet and international roaming.

Which smartphones support Vo LTE

There are more rumors about new formats of communication and voice communication than there is truth. Therefore, we will try to find out not only about Vo LTE, what is in the phone, but also about which devices support this technology. Today, smartphones supporting 4G and all related formats are not uncommon; we list some of them:

1. Samsung, Galaxy series including S3 and S4.
2. IPhone, starting with the “six”.
3. LG G Pro, Optimus.
4. ZTE.
5. Xiaomi.
6. Huawei, Sony Meizu.

This list is constantly expanding. Manufacturers understand that in 2-3 years 4G networks will become unrivaled throughout the world, so rebranding is necessary today. Vo LTE has a single standard, so buy one of the phones that support the service, there will be no difference in quality.

When buying a smartphone in a retail network or online stores, check the capabilities of the device in advance: ask the seller or read the instructions.

What you need to use the technology

To make voice calls over VoLTE, both your smartphone and your mobile operator must support this technology. As for the manufacturer Xiaomi, almost all phone models are supported. In addition, the SIM card itself must be suitable for the 4G network. If your SIM card is out of date, you can exchange it for a new one free of charge at any store of your operator. It is advisable, but not necessary, to have the latest software installed on your smartphone.

List of Russian operators providing VoLTE service in different sets of services or in separate tariff plans. Also regions of the country in which this type of communication can be used.

Does my phone support VoLTE and how do I enable it?

A device that supports this technology has a corresponding item in the settings, usually located in the “SIM cards and mobile networks” section (depending on the smartphone model and its manufacturer, this section may have a different name).
Using Redmi Note as an example, we’ll figure out how to see VoLTE support in a smartphone and how to enable it. Go to your smartphone settings and select “SIM cards and mobile networks”. Open this section.

Here, under the item “Mobile during VoLTE calls”, we can already understand that our phone supports this technology. To enable it, follow these steps:

1. Select the desired SIM card (if there are 2 cards inserted in the phone) with a short tap on its name.
2. Find the “Enable VoLTE” item and slide the switch to the on position.

That's it, VoLTE is enabled in the phone and if the operator in your region provides such a service, then you can use high-quality communication using the most modern protocol.

What to do if your smartphone does not support the technology

Modules that support VoLTE are not currently available on all phones. Without their presence, you will not be able to use the new technology.

It often happens that this function (relative to our region) is limited (blocked), and this has already been said. This is not a problem for those who have the necessary module inside the device, connected and working. There are several ways to enable this feature. If your smartphone does not support it (it looks like this: there is no button to turn on VoLTE in the mobile network settings section), try using the following combinations:

• ## 4636 ## for other devices.
• *#*#86583#*#* for Xiaomi;

On a note! When calling, you must dial only international phone numbers.

And now some information for advanced users. So, we offer a list of microcircuits used in the technology:

• MediaTek Helio P35 (for Xiaomi);
• Qualcomm 205 and later;
• Broadcom BCM21892;
• MediaTek MT6739.

Note! VoLTE Megafon is enabled by default, VoLTE MTS is activated by the command * 111 * 6 #. This feature has recently appeared for Tele2 subscribers. To activate it, dial * 219 * 1#.

How to enable or disable VoLTE on your phone

Depending on the device you are using, as well as the system in which it operates, the technology turns on and off differently. The procedure is presented in the table below.

Table 1. How to enable and disable VoLTE on different versions of Android and iOS.

What to do when an error message appears

When you try to enable VoLTE, you may receive the message “Unable to activate LTE calling. To enable LTE calling for this account, please contact your carrier." This may occur with some plans (including business packages) from some operators. Enabling VoLTE on a cellular network that has not been certified by your carrier for VoLTE may affect battery life, calls, text and other messaging, voicemail, and cellular data usage. Contact your operator for assistance.

Does a VoLTE call cost more than a regular call? How to start using this service

In the vast majority of cases, a VoLTE call will cost no more than a regular call.

In addition, no Internet traffic will be consumed. Russian operators (as far as I know) - calls using VoLTE are charged not as “Megabytes”, but as the use of the provided package of minutes.

To start using VoLTE, you need:

1. have a device that supports 4G (and directly VoLTE);
2. have the latest software version from the device manufacturer;
3. in the device settings (in the “Mobile network” section) there must be permission for VoLTE to work). How to enable this technology is described below;

   VoLTE disabled

4. you need to be in an area where the 4G network operates (there are still plenty of places without 4G in Russia);
5. As for the activation of VoLTE calls, it is somehow special. There is no need to “call”; by default, the smartphone itself will try to use this technology (in the note for the call you can see a message related to “HD Voice”).

Setting up VoLTE correctly: step-by-step guide

For correct and detailed setup, complete the following tasks in order:

1. Make sure your smartphone supports VoLTE, remember that this is indicated by the presence of a suitable chip;
2. Make sure your telecom operator provides communication services using VoLTE protocols;
3. Check if your device has a VoLTE enable point in the network and Internet settings;
4. If there is no enable point, we dial special USSD combinations to unlock in our region (the enable function will appear in the menu);
5. If the unlocking was successful, press the power button and restart the phone for the settings to take effect.
6. If the function is enabled (the VoLTE section appears in the menu), the smartphone has a chip, but VoLTE did not work automatically, so check that the number is entered correctly. You can call the network using new technology by dialing a telephone number in international format.

VoLTE in Russia

In Russia, VoLTE is developing gradually. To implement this standard, it is necessary to update networks and improve the quality of 4G signal reception. One of the leaders in this direction is MTS, which has connected VoLTE in the largest number of regions.

VoLTE on Megafon is available only in a few cities:

• Moscow.
• Saint Petersburg.
• Tolyatti.
• Samara.

This list is current at the time of writing. The company continues to develop networks and plans to connect other regions to this new technology. You can find out the current list of cities on the official website - https://megafon.ru/services/communicate/hd_golos_v_4g/.

How can I turn off or deactivate

Disabling the option on smartphones with the Android operating system is the same, regardless of the brand of the device. To disable the service you will need:

1. Open the Settings menu.
2. Select the "Connections" section.
3. Click Mobile Networks.
4. Find the "VoLTE Calls" entry.
5. Disable the option by dragging the slider to the left.

Apple iPhone smartphone users need to do the following:

1. Open the "Settings" section.
2. Find "Mobile" in the list.
3. Tap Data Options.
4. Select the “Enable LTE” subsection.
5. Click Voice & Data.
6. Disable the service.

Problems enabling VoLTE

Even if the smartphone supports VoLTE, the function may not work for some reason. If the call does not go through 4G (you cannot use the Internet during calls), you need to try the following:

1. Check with your operator to see if your SIM card supports 4G. For this, each operator has a special USSD command. Sometimes it may be necessary to change the SIM card at a communication store.

2. Check if there is a 4G network available: this icon should appear on the top bar.

3. For some carriers, VoLTE will not work if the caller ID and dial tone protection options are enabled.

4. In a device with two SIM cards, VoLTE will only work with the main one. To improve the quality of communication, some models have the function of transferring mobile Internet through a second SIM card during calls via VoLTE. But you need to be prepared that the traffic from the second SIM card will be used up.

Key benefits of VoLTE

VoLTE has advantages and disadvantages. Let's list the advantages:

• The capacity of the communication standard allows you to process data from a large number of mobile devices simultaneously without overloading the network. You can appreciate the advantage only when there is a heavy load on the base stations of cellular operators, for example, at major international competitions or on New Year's Eve.
• Communication quality – a digitized signal does not imply the presence of interference. The system uses High Definition Voice technology. Thanks to it, the spectral palette when transmitting voice expands, it becomes better and more multifaceted. The HD effect for voice is achieved thanks to the Adaptive Multi-Rate Wideband audio codec.
• Data is transmitted via the Internet, but it is not charged by operators per megabyte.
• Some mobile companies provide calls via LTE to other countries at domestic prices.
• Voice communication does not affect the parallel operation of the Internet. With a classic voice call, the phone has to switch from a 4G connection to working with lower-generation communication modules - 2G and 3G. This significantly slows down or completely blocks access to the Internet for data transmission during a call.

There should be no problems with communication in areas of stable reception. Long-Term Evolution (4G) offers speeds of 170-300 Mbit/sec, which is sufficient for transmitting voice messages.

Dialing over 4G is almost instantaneous due to high connection speeds. The statement is only valid if both subscribers transmit voice over 4 worship networks. If you call subscribers of city networks or to cell phones that operate via 2G-3G, then you will not be able to squeeze the maximum speed out of VoLTE.

For more information about the benefits of Voice over LTE, watch the video

More information about VoLTE

There is another way to find out if your smartphone has VoLTE. Even if your phone has Voice over technology, it may be disabled. This can probably be determined from the device documentation. Review the brochures included with the kit. You will definitely find the information you need in them. You should also know that if your device doesn't support it, no third party app will help. You'll have to change your favorite phone.

It's not just devices that can't support VoLTE. Your SIM card may not be designed to use it. For example, in Megafon you can check your SIM card using the USSD command - * 507 #. If it doesn't fit, replace it with a new one free of charge. This can be done at the nearest appropriate communication store. Contact your dealer for assistance in using the next generation network.

Article title VoLTE - what's in the phone and how to disable it Description With the development of digital technologies, it is not surprising that even an experienced user gets confused in the names and terms. About the rest. The topic of this article will be VoLTE - what's in the phone and how to disable it. If such technology is needed, how to determine whether it is in a smartphone - all these and other problems will be solved. You will learn all the details, and you will also be able to decide for yourself whether you need to disable it. Author Igor Publisher name Igor Publisher Logo

Why is VoLTE needed?

VoLTE mainly solves the problems of quality and speed of voice communication on mobile phones. Previously, a smartphone connected to a 4G/LTE network to use the Internet would switch to the 2G/3G network when an incoming or outgoing call was made. Now calls can be made on the same LTE network, which reduces connection delay and improves sound quality due to higher bandwidth and modern voice protocols. At the same time, calls via VoLTE are charged like regular calls, Internet traffic is not consumed.

Currently, many cellular operators are actively introducing VoLTE into their infrastructures in order to retain customers and compete with various VoIP applications that smartphone owners install to make calls over the Internet.

According to the Ministry of Digital Development, Communications and Mass Communications, voice traffic in Russia is declining as the number of smartphones increases, and users are increasingly using alternative channels for communication.

Prospects

Cellular operators are seeking to upgrade their equipment to VoLTE technology. The most famous mobile operators in Russia are gradually rolling out support for VoLTE, but for now the technology remains available only in large cities. At the same time, the issue of compatibility remains open: for some communication providers, VoLTE can only be used if the tariff plans and a certain set of services match.

Why didn't we make calls over 4G before?

The main problem with voice over LTE was that 4G LTE is a data-only connection, so it did not natively support voice calls. And for calls, 3G and 2G connections were developed, and only then the Internet was added. Therefore, developers had to create new protocols to support voice communications over LTE, and this is a large amount of work that requires the restructuring of the entire voice communications infrastructure.

Sources

• https://ocomp.info/volte-chto-eto-takoe.html
• https://it-doc.info/vo-lte2/
• https://ru.wikipedia.org/wiki/VoLTE
• https://bezlimit.ru/blog/chto-takoe-volte-na-telefone/
• https://rAndroid.ru/hardware/na-telefone-poyavilsya-znachok-vo-lte-chto-eto
• https://migadget.ru/faq/volte-na-xiaomi.html
• https://club.dns-shop.ru/blog/t-78-smartfonyi/20045-volte-tehnologiya-dlya-gurmanov-golosovoi-svyazi/
• https://shop.mts.ru/news/chto-takoe-volte-i-na-kakikh-smartfonakh-rabotaet/
• [https://droidov.com/volte-chto-eto-takoe-v-telefone-dlya-chego-nuzhno-i-kak-rabotaet]
• [https://itdesc.ru/volte-chto-eto-takoe-v-telefone-i-kak-otklyuchit/]
• [https://it-tehnik.ru/gadgets/znachok-volte.html]

What is VoLTE

VoLTE stands for Voice over Long Term Evolution (voice over LTE). LTE is a data exchange protocol in wireless Internet networks, several times faster than 3G connections in speed. With its help, you can watch videos in HD quality and quickly download large files.

Previously, LTE technology was used only for data transmission and communication between the subscriber and the Internet. With the advent of VoLTE, voice transmission over the high-speed Internet connection available on mobile phones has become possible.

VoLTE is based on the IMS (IP Multimedia Subsystem) architecture, which is designed specifically for transmitting multimedia using the IP protocol in a cellular environment.

The SIM card must support an LTE network to access VoLTE capabilities. If the smartphone supports SMSoIP, then sending SMS via VoLTE is possible.