Introduction to Circuit Switched Fallback
In the realm of telecommunications, the term “Circuit Switched Fallback (CSFB)” refers to a mechanism that enables the provision of voice services over Long-Term Evolution (LTE) networks using the existing 2G or 3G circuit-switched networks.
Let’s take a step back and understand the context. With the advent of LTE, mobile networks have been transitioning towards Internet Protocol (IP) based packet-switched technologies, which offer faster data speeds and support for a wide range of multimedia services. However, this transition poses a challenge when it comes to voice calls, as the traditional circuit-switched voice networks, such as Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS), have been the backbone of voice communication for many years.
To address this challenge, operators have implemented CSFB as an interim solution. The basic concept behind CSFB is to route voice calls over the circuit-switched networks when a user on an LTE network initiates or receives a voice call. This means that the user’s device temporarily falls back to the older generation networks for voice communication while still benefiting from the high-speed data capabilities of LTE for other services.
How does CSFB work in practice?
Let’s say a user with an LTE-capable device initiates a voice call. The LTE network, recognizing the need for voice services, triggers the CSFB mechanism. The user’s device, instead of utilizing the IP-based LTE network for voice transmission, hands over the call to the circuit-switched network (2G or 3G) via a pre-established connection. The call is then completed over the circuit-switched network as if the user were on a non-LTE device.
During this process, the user’s LTE connection temporarily pauses or suspends while the voice call is ongoing. Once the call ends, the device rejoins the LTE network and resumes using the IP-based services.
CSFB allows operators to utilize the existing circuit-switched infrastructure for voice services while ensuring a smooth transition to LTE for data services. It provides a means for operators to provide voice services to LTE-capable devices without the need for immediate investment in IP-based voice solutions.
While CSFB has been an effective interim solution, the industry is gradually moving towards newer technologies like Voice over LTE (VoLTE) and Voice over WiFi (VoWiFi) for a fully integrated IP-based voice experience on LTE networks.
In Summary
In summary, Circuit Switched Fallback (CSFB) is a mechanism that enables voice services on LTE networks by utilizing existing circuit-switched networks. It allows users with LTE devices to make and receive voice calls by temporarily falling back to the older generation networks. CSFB ensures a smooth transition to LTE for data services while utilizing the existing infrastructure for voice communication. However, as the industry evolves, newer technologies like VoLTE and VoWiFi are emerging as long-term solutions for IP-based voice communication on LTE networks.
Reference Articles
Read also
[Google Chrome] The definitive solution for right-click translations that no longer come up.