Webhook Tool Filler Messages Now Available for Telnyx AI Assistants

Telnyx launched filler messages for AI Assistants, allowing developers to script utterances during webhook tool calls to keep callers engaged instead of facing silence. The feature supports deterministic, tiered messages at request start and after configurable delays, improving voice AI call retention.

Contact us https://telnyx.com/contact-us Log in https://portal.telnyx.com AI Assistants can now speak scripted utterances at the start of a webhook tool call and during long-running requests. Callers stay engaged while the assistant waits on an external API, database lookup, or third-party model, instead of sitting in silence. Silence is where voice AI calls die. A webhook tool call that takes 8 to 12 seconds for a database lookup or third-party API leaves the caller staring at dead air, and on a phone call that reads as broken, not loading. Most voice platforms either go silent and lose the caller, or ask the LLM to improvise filler, which rambles, drifts off-brand, and can't be tuned. This lets you script the wait-state UX the same way you script the conversation flow. "Let me look that up for you" at the start, "still working on this" at 5 seconds, "almost there" at 15 seconds. Deterministic, tiered, and per-tool. The same control you have over the conversation now extends to the gaps the conversation depends on. Each filler message has a type of request start spoken immediately when the tool call begins or request response delayed spoken after timing ms milliseconds if the response has not yet arrived . The timing ms field accepts 100 to 120000 ms and is only required for delayed messages. Once the response arrives, any remaining delayed messages are skipped. { "filler messages": { "type": "request start", "content": "Let me look that up for you." }, { "type": "request response delayed", "content": "Still working on this.", "timing ms": 5000 }, { "type": "request response delayed", "content": "Almost there.", "timing ms": 15000 } } Learn more in the AI Assistants docs https://developers.telnyx.com/docs/inference/ai-assistants or the Telnyx docs https://developers.telnyx.com .