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

# Troubleshooting

> Common issues and how to resolve them

## Call Fails Immediately

**Symptoms:**

* You dial the number, it rings once, then disconnects.
* Or you hear "The number you have dialed is not in service."

**Possible Causes:**

1. **No Assigned Agent**: Did you assign the phone number to an agent? Check [Assign Phone Number](/api-reference/agents/assign-phone).
2. **SIP Configuration**: If using BYOC, check that your carrier's "Origination URI" matches the one provided by Butter AI exactly.
3. **Permissions**: Ensure your account has credits/balance.

## Agent is Silent

**Symptoms:**

* The call connects, but the agent never speaks.

**Possible Causes:**

1. **Speak First**: Is `speak_first` set to `false`? Try saying "Hello" to see if it wakes up.
2. **LLM Error**: The primary LLM provider might be down or rate-limited. Check the logs for 429 errors. To prevent silent failures during outages, configure an `llm_fallback_provider` and `llm_fallback_model` in your agent settings.
3. **TTS Error**: The Voice ID might be invalid. Double-check your agent config.

## Latency is High

**Symptoms:**

* There is a 2-3 second delay before the agent responds.

**Solutions:**

* See [Latency Optimization](/best-practices/latency-optimization).
* Check if you are using a slow LLM model (e.g., GPT-4 legacy).
* Check if you are using a high-latency TTS voice.

## Tool Calls Failing

**Symptoms:**

* Agent says "I'm having trouble checking that right now."

**Debugging:**

1. **Check Logs**: Look for the tool execution logs in the Dashboard.
2. **Timeout**: Did your API take longer than 5 seconds to respond? The agent will time out.
3. **Schema Mismatch**: Did the LLM generate arguments that don't match your JSON schema? Improve the tool description to guide the LLM.