Merge pull request #535 from signalwire/august-20260803-tts-byok

TTS: state that only catalog voices resolve; document custom/cloned voice options

Author: hey-august

fern/products/platform/pages/calling/voice/TTS/cartesia.mdx

@@ -37,6 +37,12 @@ All Cartesia voices can be used with any model.
 
 ## Voices
 
+<Warning>
+Only voices from SignalWire's catalog below resolve on the platform. Voice IDs from your own
+Cartesia account — including custom or cloned voices — will not work.
+See [Custom and cloned voices](/docs/platform/voice/tts#custom-and-cloned-voices) for details.
+</Warning>
+
 Press play to audition any Cartesia voice, then **copy config** to grab the value for SWML or your SDK.
 
 <VoiceWidget provider="cartesia" />

fern/products/platform/pages/calling/voice/TTS/elevenlabs.mdx

@@ -23,6 +23,13 @@ Consult ElevenLabs' documentation for an up-to-date list of available models and
 
 ## Voices
 
+<Warning>
+Only voices from SignalWire's catalog below resolve on the platform. Voice IDs from your own
+ElevenLabs account — including custom or cloned voices — will not work by default.
+ElevenLabs voice import is available by request:
+see [Custom and cloned voices](/docs/platform/voice/tts#custom-and-cloned-voices) for details.
+</Warning>
+
 Press play to audition any ElevenLabs voice, then **copy config** to grab the value for SWML or your SDK.
 
 <VoiceWidget provider="elevenlabs" />

fern/products/platform/pages/calling/voice/TTS/index.mdx

@@ -40,6 +40,10 @@ Choose a provider to browse and audition its full voice catalog. Press play to a
 grab the engine and voice values for your SWML or SDK code. Each provider's complete voice list
 lives on its reference page, linked in the table below.
 
+Only voices from SignalWire's catalog resolve on the platform — voice IDs from your own provider
+account will not work. See [Custom and cloned voices](#custom-and-cloned-voices)
+for supported options.
+
 <VoiceWidget groupBy="none" />
 
 ## Compare providers and models
@@ -108,9 +112,26 @@ For detailed instructions for each provider, consult the voice ID references lin
 | OpenAI          | `openai.alloy`                                  | [Reference](/docs/platform/voice/tts/openai#usage)           |
 | Rime            | `rime.luna:arcana`                              | [Reference](/docs/platform/voice/tts/rime#voices)            |
 
-<br/>
+## Custom and cloned voices
 
----
+SignalWire's TTS integrations run on SignalWire's own accounts with each provider.
+When you set a voice string like `elevenlabs.<voice_id>` or `cartesia.<voice_id>:<model>`,
+SignalWire resolves the voice ID against its own provider account —
+not yours.
+
+<Warning>
+Only voices from SignalWire's catalog resolve on the platform.
+A voice ID from your own provider account — including custom or cloned voices — is not visible
+to SignalWire's account. It will not resolve, and TTS falls back to a default voice at call time.
+This applies even though a cloned-voice ID looks identical in format to a catalog voice ID.
+</Warning>
+
+ElevenLabs custom and cloned voices can be imported into SignalWire's catalog by request.
+[Contact Support](https://support.signalwire.com/portal) to request a voice import.
+Once the voice is imported, use it with the standard
+[voice string format](/docs/platform/voice/tts/elevenlabs#usage).
+
+<br/>
 
 ## **Pricing**