This attribute indicates the current IWF to mobile window size
negotiated by the Radio Link Protocol (RLP) during Exchange
Information (XID). The window size is the maximum number of
sequentially numbered Information (I) frames that may be
unacknowledged at any given time. GSM specification 4.22 defines
the range as 0 to 61. The value used for XID negotiations can be
provisioned by component GsmIwfRadioLinkProtocol attribute
iwftoMsWindowSize.