This read-write yes/no setting enables fallback to 4.8 Kbps with double buffering, the more jitter-resistant version of ifvceRate4k8x1 at the lowest supported rate. It is the option to reach for when a link is both severely bandwidth-constrained and jitter-prone, accepting the most latency in exchange for the most robustness. For example, an administrator managing a badly congested and jittery WAN link might enable this object as the final fallback tier before calls would otherwise be dropped.