Cartesia Voices and Outbound Voicemail Fixes

v26.8.25

Published: August 25, 2026

This week's update to the Syllable Agentic Platform adds Cartesia as a voice provider, with eighteen voices selectable when configuring an agent and previewable before you commit to one. It also fixes three problems on outbound calls that reach voicemail: the message is now actually left in the mailbox rather than only recorded in the transcript, a filler phrase is no longer captured into the recording the recipient hears, and a call answered with silence times out instead of staying connected. Agents running GPT-5.6 Luna also handle a silent caller turn correctly.

Voices

• Added Cartesia as a supported voice provider so that eighteen new voices can be selected when configuring an agent, with the Test button playing a preview before one is chosen.

Campaigns

• Fixed outbound calls reaching a voicemail system with a short recording window so that the message is actually left in the mailbox instead of only appearing in the session transcript.
• Stopped bridge phrases from playing before an outbound voicemail message so that a filler phrase is no longer recorded into the voicemail left for the recipient.
• Added a default 10-second pre-speech timeout to voicemail detection v2 so that an outbound call answered with silence ends instead of staying connected indefinitely.

Agents

• Added silence-token handling for GPT-5.6 Luna so that agents running on that model treat a silent caller turn as no input instead of missing it.