What is SRVCC (single radio voice call continuity)

SRVCC (Single Radio Voice Call Continuity) Explained in Detail

SRVCC, or Single Radio Voice Call Continuity, is a technology employed in mobile networks to ensure seamless handovers between voice calls established using VoLTE (Voice over LTE) and legacy 2G (GSM) or 3G (UMTS) networks. It allows users to maintain an ongoing voice call even when transitioning between areas with and without LTE coverage.

Understanding the Need for SRVCC:

• While LTE offers significant advantages in terms of data speeds and latency, its coverage might not be ubiquitous yet. Users on the move might encounter areas with limited or no LTE coverage.
• Traditional voice calls rely on circuit-switched networks like GSM or UMTS. VoLTE calls, however, utilize the packet-switched nature of LTE for voice communication.

SRVCC Bridges the Gap:

• SRVCChelpss to bridge the gap between these two technologies. When a user with an active VoLTE call moves to an area with limited or no LTE coverage, the network can initiate an SRVCC handover.
• This handover process involves seamlessly transitioning the ongoing voice call from the VoLTE session to a circuit-switched connection on the available 2G or 3G network.

SRVCC Handover Process:

1. Detection: The mobile device (UE) and the network continuously monitor signal strength and available network types.
2. Triggering: When the network detects a decline in LTE signal strength that might lead to call drop, it triggers the SRVCC handover process.
3. Negotiation: The network and the UE negotiate the handover parameters, including the target 2G/3G cell and the ciphering algorithm to be used.
4. Voice Transfer: The ongoing voice stream is transferred from the VoLTE session to the circuit-switched network.
5. Completion: Once the voice stream is successfully transferred, the call continues uninterrupted on the 2G/3G network.

Benefits of SRVCC:

• Seamless Call Continuity: SRVCC ensures users experience minimal disruption or call drops during handovers between LTE and legacy networks.
• Improved Network Efficiency: By utilizing existing 2G/3G infrastructure for voice calls in areas with limited LTE coverage, SRVCC optimizes network resource utilization.
• Enhanced User Experience: SRVCC allows users to maintain their voice calls even when moving between coverage areas, leading to a more consistent and reliable experience.

Challenges of SRVCC:

• Latency Increase: Handovers can introduce a slight increase in call latency compared to pure VoLTE calls due to the inherent differences between packet-switched and circuit-switched networks.
• Network Dependence: The success and performance of SRVCC handovers hinge on the availability and quality of the underlying 2G/3G network infrastructure.
• Battery Consumption: Handoff procedures can consume slightly more battery power compared to a stable VoLTE call.

Future of SRVCC:

• With the ongoing rollout of 5G networks, SRVCC is expected to remain relevant as a mechanism for ensuring voice call continuity during handovers between 5G and legacy networks.
• However, as 5G coverage becomes more widespread and advancements in voice over New Radio (VoNR) technology mature, the reliance on SRVCC might gradually decrease.

Additional Notes:

• The specific implementation details and trigger thresholds for SRVCC can vary depending on the network operator and their network configuration.
• Security measures are crucial during SRVCC handovers to ensure call privacy and maintain secure communication channels.

I hope this explanation clarifies the technical aspects of SRVCC (Single Radio Voice Call Continuity) and its role in maintaining voice call continuity during mobile network handovers.