Modern Xiaomi smartphones, which run on the shell of MIUI or HyperOS, display many indicators in the status bar, the value of which is not always obvious to the user. One of the most common, but not always understandable, designations is the acronym HD, which appears next to the icon of the signal level of the mobile network. Many device owners mistakenly believe that this symbol is associated with the quality of the display or video recording, but its functional purpose lies exclusively in the plane of telecommunications technology.
This icon shows that your device has successfully connected to a network of a carrier with high-definition voice technology, not just a marketing tag, but an indicator of active service that dramatically changes the quality of voice communication. Unlike the old standards, where voice was transmitted with strong distortions and narrow bandwidth, it uses digital packet data exchange, which provides crystal clear sound.
In this article, we will examine the technical nature of this phenomenon, examine the differences between normal HD and the marketing term HD+, and provide step-by-step instructions for activating the function if it does not work automatically. Understanding these processes will allow you not only to get rid of the extra icon if it interferes with you, but also to ensure the best quality of communication in all conditions.
Technical essence of VoLTE technology
HD in mobile is a visual representation of Voice over LTE (VoLTE) technology. Traditional voice calls on 2G and 3G networks used circuit switching, which limited audio bandwidth and often led to background noise, crackling and indistinct speech. VoLTE technology transmits voice as a data stream through a fourth-generation LTE network, allowing for wider frequencies and modern audio compression codecs.
When you see the badge HD, This means that the call is made through IP-It's a protocol, similar to messenger data, but with priority in the operator's network, which not only provides high-quality audio, but also provides almost instantaneous connection — the subscriber hears the beeps or picks up the phone through the operator's network. 1-2 seconds after the set, whereas in old networks the wait could last 5-7 And it also allows you to talk and use high-speed Internet at the same time. 4G, What was not possible in third generation networks.
To work this feature requires support from three components: the smartphone Xiaomi, SIM-The operator must have a deployed infrastructure. IMS (IP Multimedia Subsystem), and the phone settings must activate the appropriate switch, so if at least one of these elements is missing or configured incorrectly, the phone will automatically switch to a standard voice call, and the icon will be used. HD disappear from the state line.
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Sound quality in HD-The mode depends not only on the technology, but also on the codec that both subscribers use. HD, The connection will be normal, even if you have a corresponding icon on fire.
Differences between HD, VoLTE and Wi-Fi Calling
Users often confuse the various indicators of communication quality, but there are significant technical differences between them. VoLTE is the technology itself for voice transmission over LTE networks, which is the indicator of the HD icon. Wi-Fi Calling is an alternative method for making calls over a Wi-Fi network where there is no cellular signal or extremely weak. Although both methods provide high sound quality, they use different data channels.
It is important to understand that the HD icon appears when using the operator's cellular network. If you are in a bad reception zone, but connected to a wireless network, the phone can switch to Wi-Fi Calling, which is often indicated by a separate icon of the phone with the Wi-Fi symbol. In some MIUI configurations, when Wi-Fi Calling is active, the HD icon can also be displayed, since the sound quality remains high, but technically the traffic goes through the ISP, not through the cell tower.
Below is a table comparing the main characteristics of these technologies for a deeper understanding:
| Characteristics | VoLTE (HD) | Wi-Fi Calling | Regular call (3G/2G) |
|---|---|---|---|
| Transmission channel | LTE network (4G/5G) | Internet (Wi-Fi) | 3G or 2G network |
| Sound quality | High (Wideband) | High (depending on the internet) | Low (narrow stripe) |
| Simultaneous Internet | Possible at high speed | Possible. | Only 2G (slow) or break |
| Connection speed | Instantly (1-2 seconds) | Quickly. | Slowly (5-10 sec) |
What happens if the traffic on the tariff ends?
What does HD+ mean in Xiaomi smartphones
The term HD+, which is often found in the specifications of Xiaomi, Redmi and Poco smartphones, but has no relation to the quality of telephone communication. In this context, "+" denotes the resolution of the screen and its format. If the standard HD resolution is 1280×720 pixels with an aspect ratio of 16:9, then HD+ implies increased image height, for example, 1600×720 or 1480×720 pickels.
This marketing designation is used to describe the extended format displays that became the industry standard after 2017, which allow you to hold the device with one hand while maintaining a large diagonal for viewing content. The presence of an HD+ mark in the model name (for example, Redmi 9A HD+) speaks only about the characteristics of the matrix and pixel density, but does not guarantee support for VoLTE technology, although it is almost always present in modern devices.
Don’t confuse the status bar indicator, which you can turn on or off in the settings, with the physical characteristic of the screen, which is indicated on the box or in the store. If you choose a phone and see HD+, it’s only about the clarity of the picture and the size of the desktop, not about the quality of future calls.
How to enable HD icon display on Xiaomi
In most cases, modern Xiaomi smartphones automatically activate the VoLTE function when installed. SIM-However, in some regions or when using certain firmware, this option must be enabled manually. SIM-Maps and mobile networks, then click on your operator name.
In the menu that opens, find the Use VoLTE or Enable VoLTE switch. If you don't, try activating the engineering menu by typing the code ##86583##. Once you enter the command, a notification "VoLTE carrier check was DISABLED" (or ENABLED) should appear, which will unlock the hidden item in the settings. Be careful when using engineering codes and do not change other settings unnecessarily.
☑️ Testing of VoLTE Readiness
Once the function is activated, restart the device. If the operator supports the technology and you are in the coverage area, the desired abbreviation should appear next to the signal level indicator. In some versions of the HyperOS shell, the path may be slightly different: Settings → Mobile network → Choice SIM-map → VoLTE settings.
Why the HD badge is missing: the main reasons
The situation where the HD icon suddenly disappears can be caused by several factors. The most common reason is to leave the coverage area of the 4G network. Once the phone switches to 3G or 2G to provide voice communication, VoLTE technology becomes unavailable and the indicator disappears. This is normal behavior of the device when the signal deteriorates.
Another cause may be temporary failures on the carrier side or maintenance work, and the icon may disappear after updating the firmware if the new network settings are not applied correctly. SIM-Older model cards that do not support standards LTE — In this case, a card replacement in the operator’s cabin is required.
⚠️ Attention: If the icon HD missing and not even appearing in the city center with a full signal, try to get it out SIM-You can wipe the contacts and paste them back, and often the oxidation of the contacts disrupts the stable connection to the network. 4G.
It’s also worth checking if 4G Only is activated in the settings without the possibility of dropping to 3G if you’re at the coverage boundary. Sometimes resetting the network settings to factory settings through the Settings menu → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth helps.
The impact of VoLTE on battery charge and traffic
There is a common myth that using VoLTE significantly speeds up battery drain. In practice, the energy consumption when calling over LTE is comparable or even lower than in 3G networks, thanks to more efficient use of the radio module and reduced connection time. The smartphone does not need to constantly switch between 2G/3G modes for voice and 4G for the Internet, which reduces the load on the processor and modem.
As for internet traffic, voice calls via VoLTE are not usually charged by operators as internet traffic, even if technically data is transmitted via a network. IP-The operators allocate this traffic to a separate channel, but if you don't have unlimited minutes, the call will be spent from a packet of voice minutes of the tariff, not a megabyte.
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Using HD technology (VoLTE) does not result in critical battery consumption, and in scenarios with poor signal, 3G can even extend battery life through a more stable connection.
However, constantly searching for a 4G network in an unstable reception zone can consume more power than a stable 3G operation. If you are in a place where the LTE signal is constantly jumping, and the HD icon appears and disappears, it makes sense to temporarily force the phone to switch to 3G mode to save charge.