How capacity works#

A DID number can use channels included with the DID number service, Capacity assigned directly to the DID number, or Capacity shared through a Capacity group. These resources allow DID numbers to handle more simultaneous inbound calls, support temporary traffic increases, and control how inbound call resources are allocated across one or more DID numbers.

Capacity is evaluated automatically when inbound calls arrive. DIDWW checks the available Capacity resources for the DID number and uses the highest-priority resource that is available.

For example, a DID number can use included channels first, then dedicated channels, then shared channels, and finally metered channels if higher-priority resources are already in use.

The following example shows how DIDWW evaluates available Capacity resources when an inbound call arrives.

        ---
config:
  layout: dagre
---
flowchart LR
    classDef decision stroke:#fb923c,fill:#fef3c7,stroke-width:2px
    classDef action stroke:#22c55e,fill:#dcfce7,stroke-width:2px
    classDef outcome stroke:#ef4444,fill:#fee2e2,stroke-width:2px
    classDef input stroke:#38bdf8,fill:#e0f2fe,stroke-width:2px

    A([Incoming call]):::input
    B{"Included channels available?"}:::decision
    C["Use included channels"]:::action
    D{"Dedicated channels available?"}:::decision
    E["Use dedicated channels"]:::action
    F{"Shared channels available?"}:::decision
    G["Use shared channels"]:::action
    H{"Metered channels available?"}:::decision
    I["Use metered channels"]:::action
    J["Call rejected"]:::outcome

    A --> B
    B -->|YES| C
    B -->|NO| D
    D -->|YES| E
    D -->|NO| F
    F -->|YES| G
    F -->|NO| H
    H -->|YES| I
    H -->|NO| J

The flow starts with the Capacity that belongs most directly to the DID number and then moves through the remaining configured resources. If no Capacity resource is available, the inbound call cannot be delivered using Capacity resources.

This priority model allows different Capacity resources to work together while keeping call delivery predictable.

For Capacity type definitions and priority order, see Channel types and Capacity priority.

Capacity types#

Capacity can be provided through included channels, dedicated channels, shared channels, metered channels, or a combination of these resources.

Some resources belong to the DID number service, some are assigned directly to one DID number, and others are made available through a Capacity group. Capacity resources can also use different billing models depending on how they are configured.

For Capacity type definitions, see Channel types.

DID included channels#

Some DID numbers include inbound voice channels as part of the DID number service. These channels are the first Capacity resource used for inbound calls.

When included channels are already in use, other configured Capacity resources can provide additional concurrent call handling.

For capacity mode values, see DID capacity modes.

Dedicated channels#

Dedicated channels are flat-rate channels assigned directly to one DID number. They are reserved for that DID number and are used after included channels.

For a detailed explanation of dedicated flat-rate behavior, see Flat-rate channels.

To assign or unassign dedicated channels, see Manage dedicated channels.

Shared channels#

Shared channels are flat-rate channels assigned to a Capacity group. DID numbers in the group can use the shared channels when higher-priority Capacity resources are unavailable.

For a detailed explanation of shared flat-rate behavior, see Flat-rate channels and Capacity groups.

To assign or unassign shared channels, see Manage shared channels.

Metered channels#

Metered channels are pay-per-minute channels assigned to a Capacity group. They provide usage-based Capacity and are used after higher-priority resources are unavailable.

For a detailed explanation of metered Capacity behavior, see Pay-per-minute channels and Capacity groups.

To assign or unassign metered channels, see Manage metered channels.

Capacity priority#

When multiple Capacity resources are available, inbound calls use available resources according to a predefined priority order.

This ensures that Capacity resources are consumed consistently and that higher-priority resources are used before lower-priority resources.

For example, a DID number may have included channels, dedicated channels assigned directly to the DID number, and shared channels available through a Capacity group. Inbound calls use the available resources according to Capacity priority until no Capacity remains available.

For priority values and resource order, see Capacity priority.

Capacity groups#

A Capacity group allows multiple DID numbers to use shared channels, metered channels, or both. Groups are used when Capacity should be allocated to a set of DID numbers instead of directly to one DID number.

For Capacity group behavior, fields, and limits, see Capacity groups. To create or manage a group, see Create a capacity group and Manage DID(s) in a group.

Hybrid capacity#

Hybrid Capacity combines multiple Capacity resource types within the same Capacity configuration.

This allows inbound calls to move between available Capacity resources as call volume increases.

For example, a DID number may use included channels during normal traffic levels, dedicated or shared Capacity during higher traffic periods, and metered Capacity when all other available resources have been consumed.

The exact behavior depends on the Capacity resources assigned to the DID number and any associated Capacity groups.

For hybrid capacity priority by capacity mode and channel combination, see Hybrid capacity combinations.

When capacity is exceeded#

Inbound calls use available channels according to Capacity priority. If no configured channel is available, the inbound call cannot be delivered using Capacity resources.

Use View capacity usage to review concurrent call usage, capacity exceeded events, and reports.