MLPP functionality is now available in Vocality software at no extra cost.

Multi-level Precedence and Pre-emption (MLPP) is a protocol devised to allow high-priority users to interrupt low-priority users in a voice network where bandwidth is restricted. Vocality has implemented this across all of its analogue, digital, ISDN and SIP voice channels in response to demand from the US DoD, amongst others. The protocol allows up to five priority levels of subscriber to coexist on a network and guarantees that high-priority users can always get through, holding any interrupted calls for the duration while playing out comfort tones and then allowing the low priority call to be reinstated.

MLPP is implemented in the main Vocality software which operates in devices such as the V150 and V200.