Can I Make Calls from a VoLTE Device to a Non-VoLTE Device?

Yes, you can make calls from a VoLTE (Voice over LTE) device to a non-VoLTE device. VoLTE, designed to enhance voice call quality over the LTE network, is also built with compatibility in mind. When you initiate a call to a non-VoLTE device, typically using 3G or 2G networks, the call is routed through the appropriate network infrastructure, capable of maintaining a successful connection.

Compatibility and Network Compatibility

VoLTE, part of the 3GPP (3rd Generation Partnership Project) standards, is designed to be compatible with both the newer SIP-based networks and the legacy circuit-switched networks. This is facilitated by the IMS (IP Multimedia Subsystem), a key component of VoLTE. IMS allows for interoperability between different network architectures. When a VoLTE user is trying to call a non-VoLTE device, an MGCF (Media Gateway Control Function) plays a critical role in the process. The MGCF acts as a translator, ensuring that the SIP-based VoLTE signaling can interact with the legacy signaling protocols, such as ISUP or BICC.

The Role of MGCF

The MGCF ensures that the call can be routed to the appropriate network. This might involve determining whether to connect through SIP or ISUP, which is determined by the destination device's capabilities, often using ENUM (E.164 Number Mapping) for resolution. Once the need to reach a non-SIP network is established, IMS routes the call to the MGCF. The MGCF then translates the VoLTE signaling into the appropriate legacy signaling protocol, enabling the call to be routed to the Public Switched Telephone Network (PSTN).

Quality and Reliability of the Call

While the general concept of making VoLTE-to-non-VoLTE calls is straightforward, the quality and reliability of the call can vary. This variation is primarily due to the networks involved and the capabilities of the devices. The LTE network provides a faster and more reliable connection for VoLTE devices, but the quality could degrade if the call is routed through a less efficient network or if the devices at either end have limited signaling or signaling capacity.

Conclusion

In summary, the ability to make calls from a VoLTE device to a non-VoLTE device is a testament to the robust design of VoLTE, ensuring interoperability and connectivity across different network technologies. Whether you are on a VoLTE enabled device or a traditional 2G or 3G device, the quality of the call can be preserved if the network infrastructure can effectively handle the transition between these technologies.