FST (Fast Session Transfer)

Fast Session Transfer (FST) is a technology developed by Microsoft to enable seamless transfer of ongoing communication sessions between two devices without any interruption or loss of data. It is primarily aimed at enhancing the user experience while switching between devices or networks during a communication session. In this article, we will delve deeper into the workings of FST, its advantages, and its applications.

Before we dive into the technical details of FST, let us first understand the need for such a technology. Today, most of us use multiple devices such as smartphones, tablets, laptops, and desktops to communicate with each other over various networks such as Wi-Fi, cellular data, and Bluetooth. Often, while communicating on one device, we may have to switch to another device due to various reasons such as battery drain, network issues, or simply convenience. However, such a switch often results in a disruption of the ongoing communication session, causing frustration and inconvenience to the users.

FST aims to address this issue by providing a seamless way to transfer ongoing communication sessions between two devices without any interruption. It achieves this by transferring the entire communication context, including the session state, media streams, and user interfaces, from the source device to the target device in real-time.

Now, let us delve into the technical details of FST. FST comprises two primary components: the FST protocol and the FST engine. The FST protocol is responsible for establishing and maintaining the communication sessions between two devices, while the FST engine is responsible for transferring the ongoing communication session from the source device to the target device.

The FST protocol uses the Session Initiation Protocol (SIP) to establish and maintain the communication session between two devices. SIP is a widely used protocol for initiating, maintaining, and terminating real-time communication sessions, such as voice, video, and messaging, over IP networks. When a user initiates a communication session on a device, the FST protocol establishes a SIP session between the two devices and negotiates the session parameters, such as codec, bitrate, and transport protocol, for the ongoing communication session.

Once the SIP session is established, the FST engine takes over and starts transferring the ongoing communication session from the source device to the target device in real-time. The FST engine uses a combination of technologies such as RTP (Real-time Transport Protocol), RTCP (Real-time Transport Control Protocol), and SRTP (Secure Real-time Transport Protocol) to transfer the media streams between the two devices. RTP and RTCP are widely used protocols for real-time transmission of audio and video over IP networks, while SRTP provides a secure way to transfer the media streams over the network.

During the session transfer, the FST engine transfers the entire session context, including the session state, media streams, and user interfaces, from the source device to the target device. This ensures that the user experience remains consistent across devices, and there is no disruption of the ongoing communication session. The FST engine also ensures that the session transfer is transparent to the user, and there is no need for the user to take any action during the transfer.

FST has several advantages over traditional communication technologies. Firstly, it enables seamless transfer of ongoing communication sessions between two devices without any interruption, providing a consistent user experience across devices. Secondly, it eliminates the need for the user to manually transfer the session between devices, saving time and effort. Thirdly, it ensures that the session transfer is secure, and the media streams are encrypted during the transfer. Finally, it enables real-time communication sessions over multiple networks, such as Wi-Fi, cellular data, and Bluetooth, providing greater flexibility and convenience to the users.

FST has several applications across various industries. In the healthcare industry, FST can be used to transfer ongoing telemedicine sessions between devices, enabling healthcare professionals to seamlessly switch between devices and provide uninterrupted care to patients. In the education industry, FST can be used to enable seamless transfer of online classes between devices, allowing students to continue their education without any disruption. In the business industry, FST can be used to transfer ongoing video conferences between devices, allowing team members to switch devices and locations during the conference without any interruption.

In conclusion, Fast Session Transfer (FST) is a technology developed by Microsoft to enable seamless transfer of ongoing communication sessions between two devices without any interruption or loss of data. It comprises two primary components: the FST protocol and the FST engine. The FST protocol is responsible for establishing and maintaining the communication sessions between two devices, while the FST engine is responsible for transferring the ongoing communication session from the source device to the target device. FST has several advantages over traditional communication technologies, including seamless transfer of sessions, time and effort savings, secure transfers, and multi-network flexibility. FST has several applications across various industries, including healthcare, education, and business.