MLPP
Multilevel Precedence and Preemption Support
This feature is provided as a Supplementary Service on the primary rate ISDN interfaces available in Vocality equipment, whereby voice calls may be assigned precedence on a per call basis ranging from the lowest precedence, 4 (Routine) to highest precedence 0 (Flash Override). In the case of congestion, either at the terminating user end or within shared network resources, this precedence level may be used to pre-empt (terminate) existing low precedence calls to allow a high precedence call to complete. Preemption can only occur on calls where the parties are assigned to participate in the MLPP feature.