# Capacity

Capacity determines how many inbound calls a DID number can receive at the same time. Without sufficient Capacity, calls
that exceed the limit are rejected - meaning real callers hear a busy signal or get disconnected before reaching your
system.

DIDWW gives you three channel types to match your traffic patterns and control costs:

- **Flat-rate** - Fixed monthly channels for predictable call volumes, assigned to a single DID or shared across multiple DIDs through a Capacity group.
- **Pay-per-minute** - Metered channels for variable or unpredictable traffic, billed per minute with no setup or monthly fees.
- **Hybrid** - Flat-rate channels for baseline traffic with metered channels as automatic overflow, so you pay a fixed rate for expected volume and only pay extra when traffic spikes.

Note

Capacity applies to inbound calls only.

## Key features

- See which capacity options are available for a DID number.
- Buy, assign, and remove flat-rate channels.
- Assign extra channels directly to a DID number.
- Share channels between multiple DID numbers through a Capacity group.
- Add or remove DID numbers from a Capacity group.
- Review call usage, failed calls, and capacity exceeded events.
- Learn how Capacity is billed and how the different channel types work together.

## Get started

**How capacity works**

Understand Capacity types, priority, Capacity groups, and hybrid capacity call flow.

[How capacity works](how-capacity-works.html)

**Flat-rate channels**

Learn how dedicated and shared flat-rate channels provide fixed monthly capacity.

[Flat-rate channels](flat-rate-channels.html)

**Pay-per-minute channels**

Learn how metered channels provide usage-based capacity through Capacity groups.

[Pay-per-minute channels](pay-per-minute-channels.html)

**How-to guides**

Purchase, assign, unassign, remove, and manage Capacity channels and Capacity groups.

[How-to guides](how-to-guides/index.html)

**Capacity groups**

Understand shared and metered channel allocation, group behavior, fields, and limits.

[Capacity groups](capacity-groups.html)

**View capacity usage**

Review concurrent call usage, exceeded-capacity events, statistics, and reports.

[View capacity usage](view-capacity-usage.html)

## Related resources

**Capacity reference**

Look up Capacity fields, values, channel types, pool types, and modes.

[Capacity reference](capacity-reference.html)

**Capacity billing**

Understand included channels, flat-rate charges, setup fees, prorated billing, and metered charges.

[Capacity billing](capacity-billing.html)

**My numbers**

Manage DID-level capacity settings, group assignment, trunks, and related services.

[My Numbers](../my-numbers/index.html)

**Number billing**

Review DID number setup charges, recurring charges, billing cycles, and renewal behavior.

[Number billing](../number-billing.html)

**Logs & analytics**

Review statistics, reports, and call logs related to Capacity usage and failures.

[Logs & Analytics](../../logs-analytics/index.html)

**Inbound trunks**

Configure inbound call routing before reviewing Capacity behavior.

[Inbound Trunks](../../voice/inbound-trunks/index.html)

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