This value is the second reverse traffic descriptor parameter (typically reverse sustainable cell rate) for this failed call, per the description, complementing svcAtmFailedCallAtmRTfdParam1 to describe the sustained bandwidth requested in the return direction. Together with the other reverse parameters, this lets an admin fully characterize what the call was asking for on the return path when call admission control on this port rejected it. This detail matters mainly for asymmetric traffic profiles where forward and reverse demand diverge significantly.