What is the Difference Between CSFB and VoLTE?
Let me walk you through the key differences between CSFB (Circuit-Switched FallBack) and VoLTE (Voice over LTE), two important technologies that ensure voice calls work in LTE networks. As we’ve discussed in earlier articles, LTE was initially designed for high-speed data, and voice was not its primary focus. This led to the development of solutions like CSFB and VoLTE to handle voice calls in LTE networks. Let’s explore each one in more detail and see how they differ.
CSFB – Circuit-Switched FallBack
CSFB is a mechanism that allows LTE networks to handle voice calls by falling back to 2G or 3G networks, which still rely on circuit-switched technology for voice calls. So, when you’re making a voice call on an LTE network, it doesn’t happen over the LTE connection itself. Instead, the voice call is handed off to a 2G or 3G network, where traditional circuit-switched technology is used.
This means that when a user is on an LTE network and tries to make a voice call, the LTE network will temporarily “fall back” to the legacy 2G or 3G network. The call is established on the older network, and once the call is finished, the user is handed back to the LTE network. The process involves a break in the LTE connection during the call setup, and it can lead to slightly longer call setup times compared to VoLTE.
In essence, CSFB enables LTE devices to make voice calls by temporarily switching to a 2G or 3G network, ensuring that voice services are available even in areas where LTE coverage for voice calls is not yet implemented.
VoLTE – Voice over LTE
VoLTE, on the other hand, is a technology that allows voice calls to be made directly over the LTE network itself, without needing to switch to 2G or 3G. It uses IP (Internet Protocol) to transmit voice data as packets, just like how data is sent over LTE. The key advantage of VoLTE is that it provides high-quality voice calls, often referred to as HD Voice, and ensures that voice and data services are handled simultaneously over the same network.
With VoLTE, calls are set up over the LTE network without the need for a fallback to an older network. This leads to faster call setup times and higher-quality voice services. Since voice is carried as data, it also benefits from the enhanced capacity and efficiency of the LTE network, resulting in better call quality and more efficient use of the available spectrum.
Additionally, VoLTE supports features such as video calls and rich multimedia services, which are not possible with CSFB. It enables simultaneous voice and data usage, meaning you can be on a call while still browsing the internet or using other data services, unlike with CSFB, where the data connection is usually suspended during the call.
Key Differences Between CSFB and VoLTE
- Voice Call Technology: CSFB falls back to 2G/3G for voice calls, while VoLTE keeps the voice call on the LTE network using IP-based technology.
- Call Setup Time: CSFB usually takes longer for call setup because of the fallback process, while VoLTE provides faster call setup due to its native support on the LTE network.
- Call Quality: VoLTE offers higher voice quality (HD Voice) as it uses a more efficient codec and stays on the LTE network, whereas CSFB uses older 2G/3G networks, which may provide lower quality.
- Simultaneous Data Usage: VoLTE allows simultaneous voice and data services (you can talk and browse the internet at the same time), whereas with CSFB, data services are usually paused during voice calls.
- Network Efficiency: VoLTE is more efficient as it uses the IP protocol over LTE, while CSFB requires switching to older network technologies, which can lead to network congestion and inefficiency.
Why It Matters to You
Understanding the difference between CSFB and VoLTE is essential for users who rely on their smartphones for both voice and data services. If you’re using an LTE network, you’ll likely experience both technologies depending on your location and network setup. If you’re in an area where VoLTE is available, you’ll enjoy high-quality voice calls and the ability to use voice and data services at the same time. On the other hand, in areas where VoLTE is not yet deployed, CSFB ensures that you can still make voice calls, albeit with slightly lower quality and longer call setup times.
As we’ve learned in previous articles, LTE is primarily focused on data services, but with technologies like CSFB and VoLTE, operators have found ways to integrate voice calling seamlessly into the LTE environment. This ensures that you get a smooth and consistent experience, whether you’re browsing the internet or making calls, even as the network evolves.