CSFB

Deep Technical LabKit Use Cases

CSFB with the Legba Lab Kit

Many 4G networks cannot carry plain old telephone calls, so many mobile operators support voice calls by transferring the handset to a 2G or 3G network for the duration of the call. The procedure for doing this is called “Circuit-Switched Fallback”, or CSFB. CSFB is an interesting procedure from a network operation perspective and from a security perspective. With a pair of Legba Lab Kits, one in 2G mode and one in 4G mode, you can reproduce and modify the CSFB procedure on a test bench.