This read-only Integer32 (0..2147483647) reports the Maximum Burst Size of the call in the forward direction, the largest burst of cells the source may send at PCR before it must fall back toward SCR. An administrator uses this to understand how much burst tolerance was actually negotiated for this specific call, which affects how quickly non-conforming traffic will start being tagged or dropped during a burst. For example, an operator seeing cell tagging occur on a call after a short burst checks cwspCallFwdMbs to confirm whether the negotiated burst allowance for that call was simply too small for the traffic pattern.