This Recommendation provides reference connections, network Grade of Service (GOS) parameters, and target values at both the call and the cell level for the user-plane for ATM-based B-ISDNs. The first release of E.726 applies to calls that consist of a pair of point-to-point ATM connections providing bidirectional communication between two ATM end-points. This release also assumes that switched ATM connections are established via associated signalling as defined by Recommendations Q.2931 and Q.2761, see also E.728. This Recommendation pertains to both terrestrial and satellite-based systems.