How does voice over LTE (VoLTE) affect international calls using phone numbers?

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Voice over LTE (VoLTE) is a technological advancement that enables voice calls to be carried over the 4G LTE data network, rather than relying on traditional 2G or 3G circuit-switched networks for voice communication. Essentially, it turns your voice calls into data packets, much like how internet Browse or video streaming works. This shift to an all-IP (Internet Protocol) based voice system has several significant effects on international calls made using traditional phone numbers.

How VoLTE Affects International Calls:
Improved Call Quality (HD Voice):
One of the most noticeable benefits of VoLTE is High-Definition (HD) Voice quality. VoLTE utilizes advanced audio codecs that allow for a wider range of sound frequencies to be transmitted, resulting in clearer, more natural-sounding conversations with reduced background noise. When both the caller and receiver are on VoLTE-enabled networks, even across international borders (provided there are VoLTE roaming agreements), the difference in clarity can be significant, making international calls feel more like local ones.

Faster Call Setup Times:
Traditional voice calls on 2G or 3G networks often involve a process called "Circuit-Switched Fallback" (CSFB), where a 4G-connected phone temporarily drops to a 2G or 3G network to make or receive a voice call. This fallback adds a delay to call setup. VoLTE eliminates this fallback, allowing calls to connect much faster, often within a couple of seconds, even for international calls.

Simultaneous Voice and Data:
Before VoLTE, if you were on a 4G network and made a call, your romania phone number list phone would often drop to 2G or 3G for the duration of the call, meaning you couldn't use high-speed mobile data simultaneously. With VoLTE, your phone stays on the 4G network for both voice and data. This is particularly beneficial for international calls, as you can simultaneously browse the internet, use navigation apps, or check emails without interrupting your conversation.

Challenges with International Roaming (VoLTE Roaming Interoperability):
While VoLTE offers significant advantages, its implementation for international roaming ("VoLTE Roaming") introduces complexities:

Bilateral Agreements: For seamless VoLTE calls while roaming, your home mobile operator (HPMN) needs to have a specific VoLTE roaming agreement with the visited mobile operator (VPMN) in the country you're traveling to. Not all operators globally have these agreements in place yet.
Device and Network Compatibility: Even with agreements, there can be challenges with device compatibility. Your phone and its firmware must be configured to support VoLTE on the specific roaming partner's network. Some older phones or devices purchased from different markets might not fully support VoLTE roaming in all countries.
2G/3G Sunset: As many countries are phasing out their older 2G and 3G networks to repurpose spectrum for 4G and 5G, having VoLTE roaming capability becomes critical. If a country you visit has shut down its 2G/3G networks and your phone or operator doesn't support VoLTE roaming there, you might be unable to make or receive any voice calls (including emergency calls) using your traditional phone number while in that region. This is a growing concern for travelers.
Billing Complexity: VoLTE calls are data packets. This creates challenges for traditional per-minute wholesale roaming billing models between operators. New billing agreements are required to accurately account for and charge VoLTE roaming usage.
Routing and Signaling:
VoLTE shifts voice calls from a circuit-switched architecture to an IP Multimedia Subsystem (IMS)-based packet-switched architecture. This changes how international calls are routed and how signaling information (like caller ID) is transmitted. While the end-user still dials the familiar E.164 phone number, the underlying network processes and routes these calls differently, often routing them back to the home network's IMS core (S8HR architecture) even when roaming, before sending them to the international destination.

In Bangladesh, major operators like Grameenphone have launched VoLTE domestically and are gradually expanding VoLTE roaming agreements with international partners (e.g., Grameenphone has launched VoLTE roaming with Telenor Norway and Digi Malaysia). This reflects the global trend towards an all-IP voice future. For users in Bangladesh, if they have a VoLTE-enabled handset and a 4G SIM, and their operator has VoLTE roaming agreements in place with the visited country, they can enjoy clearer calls, faster connections, and simultaneous voice and data for their international communications using their existing phone number. However, it's always advisable to check with your operator about VoLTE roaming availability and compatible destinations before traveling.