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Retell AI

Hey! Running into an issue with the built-in `press_digit` tool - 100% of calls return `success: false` with no error message.

**Setup:**
- Model: gpt-4.1
- Telephony: Retell-managed
- Tool type: Built-in press_digit

**What's happening:**
- LLM correctly invokes press_digit (visible in transcript_with_tool_calls)
- All tool calls return `success: false`, `latency_ms: 0`, `result: null`
- No DTMF tones are actually sent
- Tested across multiple calls (47 tool calls in one, 23 in another - all failed)

**Example tool call from transcript:**
```json
{"digit_to_press": "1"}
```

**Example result:**
```json
{"tool_call_id": "72c416edf862956c", "success": false, "latency_ms": 0, "result": null}
```

The `latency_ms: 0` suggests instant rejection without attempting to send DTMF.

**Questions:**
1. Is the parameter supposed to be `digit` or `digit_to_press`? Docs don't specify
2. Any config step I might be missing for the built-in tool to work?
3. Any known issues with press_digit on gpt-4.1?

Thanks!

Hi <@1437526596519989419> 
So are you using outbound calls because press_digit tool won't work on inbound calls