APIUpcoming
The
override_dynamic_variables input on Update Call is deprecated, and Update Call becomes ended-calls-only. Changes you make through Update Call — including data_storage_setting, which previously took effect mid-call — now apply only to ended calls. Use the new Update Live Call API to override dynamic variables or change data_storage_setting on ongoing calls.Impacted API endpoints:- Update Call — field:
override_dynamic_variables
APIUpcoming
Legacy agent list endpoints will be removed. Use the unified List Agents API and filter by
channel for voice or chat agents.Impacted API endpoints:- List Voice Agents, List Chat Agents — endpoints replaced by
POST /v2/list-agents
MCPUpcoming
The legacy hosted MCP server at
retell.stlmcp.com will be removed. Point your MCP client to mcp.retellai.com instead — see the Retell MCP server guide.Impacted:retell.stlmcp.com— removed 07/20/2026. Usemcp.retellai.com(same Bearer API-key auth).
API
New API deprecation notice: Legacy agent publish endpoints.
Deprecation date: 07/20/2026.
See the migration notice for affected APIs and replacement guidance.Impacted API endpoints:
POST /publish-agent/{agent_id}POST /publish-chat-agent/{agent_id}
ModelsUpcoming
ElevenLabs Turbo voice models are being deprecated and automatically migrated to their Flash counterparts on 7/12/2026. We have confirmed with ElevenLabs and verified that Flash delivers the same voice quality at lower latency.Read more.
APIUpcoming
Legacy list endpoints and analysis prompt fields will be removed. Migrate to the versioned list endpoints (v2/v3) and to
post_call_analysis_data / post_chat_analysis_data system presets.Impacted API endpoints:- List Batch Tests, List Conversation Flow Components, List Conversation Flows, List Phone Numbers, List Retell LLMs, List Test Case Definitions, List Test Runs, List Calls, List Chats — endpoints replaced by versioned (v2/v3) equivalents
- Create Agent, Update Agent, Create Chat Agent, Update Chat Agent — fields:
analysis_summary_prompt,analysis_successful_prompt,analysis_user_sentiment_prompt
Models
Claude and Gemini models are being deprecated and automatically migrated to newer versions on 5/25/2026.Read more.
API
The
tools and tool_ids fields on type: "conversation" nodes are deprecated in favor of the new subagent node type.Impacted API endpoints:- Create Conversation Flow, Update Conversation Flow, Get Conversation Flow, List Conversation Flows, Create Conversation Flow Component, Update Conversation Flow Component, Get Conversation Flow Component, List Conversation Flow Components — fields:
tools,tool_ids(ontype: "conversation"nodes)
Models
OpenAI Realtime and Cartesia Sonic models are being deprecated and replaced with newer versions. After 4/3/2026, the deprecated models will no longer be available.Read more.
API
The single-agent fields on phone number configuration are deprecated in favor of the weighted
*_agents lists.Impacted API endpoints:- Create Phone Number, Import Phone Number, Update Phone Number, Get Phone Number, List Phone Numbers — fields:
inbound_agent_id,inbound_agent_version,outbound_agent_id,outbound_agent_version,inbound_sms_agent_id,inbound_sms_agent_version,outbound_sms_agent_id,outbound_sms_agent_version
API
show_transferee_as_caller no longer toggles SIP REFER vs SIP INVITE in Cold Transfer options. Use the new cold_transfer_mode parameter instead; show_transferee_as_caller now only controls caller ID display under sip_invite.Impacted API endpoints:- Create Retell LLM, Update Retell LLM, Create Conversation Flow, Update Conversation Flow, Create Conversation Flow Component, Update Conversation Flow Component — field:
show_transferee_as_caller