Many 4G smartphones cannot make voice calls when the 2G network stops working

In some groups about old phones on Facebook, many people complained that they started having problems hearing or calling even though the phone still had signal and had normal Internet access.

Pham Van, using a BlackBerry KeyOne, said his eight-year-old phone still accesses the Internet and uses normal applications. However, from the beginning of August, the calling function began to have problems, unable to receive and make calls. The cause was later determined to be because the 2G signal in the area was turned off, while the many-year-old phone model did not support calling on the 4G network.

“I tried following the tips to activate VoLTE but the device actually doesn’t support it. Maybe it’s time to ‘retire’ this phone,” he said.

According to the roadmap, from September 15, the 2G network will stop broadcasting nationwide, except for some specific areas. In fact, the process of turning off 2G has been gradually implemented by network operators by region. For example, Viettel said that some 2G stations in areas that meet conversion conditions have been turned off. Meaning, some customers may be affected by voice service earlier than September 15 if the device or subscription is not ready.

Network operators also warn that this will affect smartphone models with an Internet connection instead of just 2G only phones as in the 2024 service outage.

Why can 4G phones still be affected?

According to a technician from a network operator, many smartphones display 4G and access the Internet normally, but when making or receiving calls, the device still switches to the 2G network to maintain a voice connection. This process happens automatically so most users are unaware.

When 2G waves no longer exist, those phones need to make calls directly on the 4G network through VoLTE (Voice over LTE) technology. If the device does not support it, or the VoLTE feature is not enabled, or the subscriber has not activated the service, users may experience interruptions when making or receiving calls. This is also one of the reasons why Vietnam maintains this generation of networks for another two years to give users time to switch.

“Having a phone with 4G does not mean you can make calls normally after 2G is turned off,” the technician shared.

According to this person, the majority of affected subscribers are people using old phones, laptops or devices that are not officially distributed in Vietnam. With the above devices, users should proactively check the ability to call on the 4G network before the 2G signal is turned off.

How to maintain calls?

If you cannot use calls on the 4G network, users are recommended to check three factors, including whether the phone supports VoLTE, 4G/5G SIM, and whether the subscriber has activated voice service on 4G.

On multiple devices, users can enter Settings > Mobile networks or SIM and mobile network, then look for options like VoLTE, VoLTE Calls, 4G Calling or 4G Voice and Data. Feature names and locations may vary depending on brand and software version.

To use the calling feature on the 4G network, subscribers need to use a 4G/5G SIM, a device that supports VoLTE, turn on the feature on the phone and have the corresponding service activated. Most carriers today offer this for free.

If the SIM is not compatible, users need to go to a transaction point for support in changing the SIM. In case your phone does not support it, you need to switch to a 4G/5G device with similar VoLTE capabilities. In addition, the market has applications that help receive calls from telecommunications networks, but these solutions are considered for temporary use only.

Some Vietnamese carriers said they will automatically scan to activate services for users. However, they also recommend that people proactively check or go to stores, points of sale or network support points.

“Depending on each case, customers can change SIMs and access appropriate device support programs to maintain contact,” said Viettel network.

Stopping the 2G network is a step that has been proposed for many years, to free up frequency resources for new generation mobile technologies, improve infrastructure efficiency and service quality, and promote the process of transitioning users to the 4G/5G environment. The frequency band previously used for 2G networks will be used for 5G or 6G networks in the near future.