Scheduled outbound call was delayed by 6 minutes beyond the specified time window, causing customer experience issues. ## Call Details Call ID:

019a081c-e7ae-755c-b4a8-c7c2d65a69c7

Assistant ID:

8718c9ae-33b1-409b-94ba-69a7166d2178

Customer Number:

+421902698385

## Timeline (UTC) | Time | Event | Status | |------|-------|--------| |

18:51:43

| Call created | ✅ | |

18:57:00

| Scheduled earliest | ⏰ | |

19:00:00

| Scheduled latest | ⚠️ | |

19:03:00

| Actual start | ❌ 6 min late | Local Time (Slovakia UTC+2): Expected 20:57-21:00, Actual 21:03 ## Scheduling Config

json
{
  \"schedulePlan\": {
    \"earliestAt\": \"2025-10-21T18:57:00.000Z\",
    \"latestAt\": \"2025-10-21T19:00:00.000Z\"
  }
}

## Business Impact We have a web form where customers select exact time for scheduled calls. They expect Vapi to call at the specified time. Result: Poor customer experience - call started 3 minutes AFTER the

latestAt

deadline. This is unacceptable for appointment-based calling. ## Questions 1. Why did the call start after

latestAt

deadline? Shouldn't this be a hard limit? 2. Is there a known scheduling queue issue during peak hours (19:00-21:00 UTC)? 3. What is the expected variance for scheduled calls? ## Requested Solution We need reliable scheduled calling with max ±1 minute variance. Please advise: 1. Is there a way to guarantee call timing? 2. Should we use wider time windows (15 min vs 3 min)? 3. Best practices for peak-time scheduling? Note: This is not an isolated incident. The call itself was perfect (2:37 duration, successful), only scheduling was delayed. Thank you!

To reduce the risk of delayed calls, **increase your

schedulePlan

time window**—for example, set

earliestAt

and

latestAt

at least 10-15 minutes apart. This gives Vapi more flexibility to process your call within the allowed window, especially during peak hours when queuing and concurrency limits can cause delays.

json
{
  "schedulePlan": {
    "earliestAt": "2025-10-21T18:57:00.000Z",
    "latestAt": "2025-10-21T19:12:00.000Z"
  }
}

Wider windows help ensure your call is not missed due to temporary system load. For strict appointment times, consider notifying users of a possible ±5 minute variance. [See scheduling details](https://docs.vapi.ai/phone-calling/outbound-calls) Source: - [Outbound Calls – Scheduling and Queuing](https://docs.vapi.ai/phone-calling/outbound-calls)