5.5.4.1 DSP Resource ReservationDescriptionA number of resources can be reserved for particular features or services to guarantee a minimum level ofservice. Resources reserved for a particular service (e.g., conferencing) cannot be used for another service(e.g., Unified Messaging).For example, one may want to reserve resources for OGM (Outgoing Message) to ensure that recordedmessages can be played to incoming calls.The resources can be reserved for the following types of services:• VoIP (G.711)• Conference trunk• Unified Messaging• Two-way Recording• OGMNoteIt is not necessary to reserve resources for a feature to use it. In normal operation, free DSP resourcesare allocated on a first-come first-serve basis. Resources should be reserved only if a minimum level ofperformance is required for your system.For example, reserving resources for Two-way Recording (® 3.2.1.4 Automatic Two-way Recording forManager, ® 3.2.2.34 Two-way Record/Two-way Transfer) also reserves UM ports. This can have theunintended effect of blocking access to the Unified Messaging system even when no recording is beingperformed. Therefore, resources for Two-way Recording should be reserved only if it is necessary toguarantee that Two-way Recording can be performed. (® 3.1.1 Unified Messaging System Overview)Resource Reservation ExampleThe following table shows the number and types of resources that must be reserved for a given workload. Tocalculate the number of free (i.e., non-reserved) resources, a DSP M card (127 DSP resources) is assumed.Service Minimumperformance*1Resources per unit ofperformanceNo. of required DSPresourcesVoIP call (G.711) 40 calls 1 40Unified Messaging*2 5 operations 1.3 6.5Two-way Recording 3 recordings 2.3 6.9OGM 10 playbacks 2 20Conference trunk 10 conferences 0.5 5Unified Messaging tone*3 2 tones 2 2Total Reserved Resources 80.4Free Resources*4 47*1 Minimum performance refers to the minimum number of simultaneous operations.*2 Unified Messaging operations include operations such as users (subscribers) accessing their mailboxes and outside callers leavingmessages in subscribers’ mailboxes.*3 The resources for Unified Messaging tones (used for Two-way Recording) are reserved automatically and cannot be released.*4 Free Resources = DSP capacity – Total Reserved Resources, rounded to the nearest whole number.If the PBX’s resources are reserved as shown in the example above, the resources required to meet thenumbers of operations listed in the "Minimum performance" column are guaranteed to be available. Note,however, that for an operation such as a conference call, DSP resources are required for each individualconference party in addition to the resources required for the conference trunk itself. Therefore, if all 40 VoIPFeature Guide 4795.5.4 DSP Resource Usage
