> ## Documentation Index
> Fetch the complete documentation index at: https://docs.trychert.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Limits and readiness

> Plan call capacity and verify the media you need.

<a id="guarantees" />

## Capacity

A provisioned line handles **one active call at a time**. Multiple teams can share that line sequentially. For simultaneous demos, each call needs its own provisioned, ready line and an isolated agent session.

| Provisioned, ready lines | Maximum simultaneous calls, if your agent has capacity |
| ------------------------ | ------------------------------------------------------ |
| 1                        | 1                                                      |
| 3                        | Up to 3                                                |
| N                        | Up to N                                                |

These are capacity examples, not a promise of how many lines are assigned to your project. Confirm your reserved line count, FaceTime handles, and demo window with Chert. Available concurrency can be lower when a line is busy, offline, or not ready, or when your LiveKit or model-provider limits are reached.

## Plan a multi-team event

1. Decide how many teams must demo simultaneously.
2. Arrange that many independently provisioned lines with Chert, or schedule sequential slots on fewer lines.
3. Assign each team a handle and time slot. Do not assume that one FaceTime handle provides an automatic multi-call pool or queue.
4. Use a separate LiveKit room and agent session per active call. Sharing a project does not require sharing a room.
5. Rehearse all planned simultaneous calls and confirm that each line becomes ready again after hangup.

BYOR credentials and the `remote_participant_identity` can be chosen per accepted call, so the same line can serve different team agents at different times. Your webhook owns that selection; use your demo schedule or application context rather than relying on a caller hash as authenticated team identity.

## Operational limits

* **Inbound decisions:** respond within the configured decision deadline, five seconds by default. Missing or invalid decisions fail closed.
* **Bridge tokens:** include valid integer `nbf` and `exp` claims with `exp - nbf` no greater than 7,200 seconds.
* **Audio participants:** provide exactly one eligible remote participant with one unmuted published audio track. Silent auxiliary participants may be present.
* **Outbound idempotency:** use an `Idempotency-Key` of 8–200 characters. Reuse it when retrying the same creation request.
* **Readiness:** an available line can still have an offline or unready worker. Inspect current worker readiness before testing.
* **Video:** video calls carry media in both directions. Subscribe to the caller's video track and handle camera mute or track removal; audio-only calls do not include video.

See [BYOR](/facetime/bring-your-own-room) for credentials and media requirements.