Synthflow

Overview

Synthflow is an enterprise voice AI platform for automating inbound and outbound phone calls, aimed at contact centres and business process outsourcers rather than at individual developers. Agents are assembled either in Flow Designer, a node-based canvas with conversation, message, branch, jump and custom action nodes, or in a simpler prompt builder, and one agent can hold several specialised flows through a multi-agent system. Actions book meetings, transfer calls, call external APIs and send SMS or WhatsApp messages mid-call, and IVR handling, manual testing and custom evaluations that score calls against business goals sit alongside them. It connects to existing telephony over SIP trunking, including SIP X-headers passed into prompts and transfers, and to CRM and contact centre systems through what the vendor counts as over 200 integrations. White-labelled deployments let a partner put its own brand on the agents it resells. There is no self-serve tier: the published plan is an enterprise contract that bundles implementation, onboarding, testing, training and launch support.

Best for contact centres and outsourcers that want phone agents built, branded and launched under one contract.

Synthflow is the option in this category that is bought rather than assembled, and the pricing page says so plainly: an enterprise contract with a floor in the tens of thousands, with the implementation work priced into it. For a contact centre or an outsourcer running someone else's phone estate, that is the point, and the white-label layer and the SIP and CCaaS connections are what a services business actually needs to resell the thing. For anyone who wants to try a voice agent against a real number this week, it is the wrong shape entirely, and the developer-billed platforms in this category are a better first stop. The published latency figures differ between the vendor's own pages, so treat that number as something to measure on your own traffic during a pilot rather than as a specification.

Key Facts

Features

Voice cloning

Cloning happens in ElevenLabs, not in Synthflow. The voice selector offers Synthflow's own TTS with twelve built-in voices and the ElevenLabs models from Turbo v2 and Flash v2.5 up to v3; a cloned or provider-specific voice is added through Imported > Import Voice by pasting the provider voice ID, or by connecting your own ElevenLabs API key so that account's custom voices appear in the selector. The vendor warns that a synthesiser model your own ElevenLabs plan lacks can mean lower quality or higher latency on your key

Real-time use

Yes, live inbound and outbound calls, with IVR handling for outbound agents, voicemail and silence handling, in-call SMS and WhatsApp messaging, and WhatsApp Business calling. The vendor states 99.99% uptime on its own telephony infrastructure

Languages

Over 30 languages are listed in the documentation, plus a multilingual mode that switches between English, Spanish, French, German, Hindi, Russian, Portuguese, Japanese, Italian and Dutch within a single call. Speech recognition runs on Deepgram or Synthflow's own engine, which the vendor recommends for non-English

Speech-to-speech and dubbing

Not documented. The voice documentation covers text-to-speech for live agents, with a speaker and a synthesis model chosen per agent, and carries no speech-to-speech conversion and no dubbing

Editing and controls

Flow Designer, a node-based canvas with conversation, message, branch, jump and custom action nodes, or a simpler prompt builder, plus a multi-agent system for several flows behind one agent, voice model and pacing settings, manual testing, automated simulations and custom evaluations that score calls against business goals

Consent and trust

SOC 2, HIPAA, PCI DSS, GDPR and ISO 27001, with encryption, audit logs and region-based hosting. Per-agent controls decide whether recordings and transcripts are kept at all, cap retention at 30 days, and redact personal data from transcripts, webhook payloads and logs

API

Yes, a public Platform API for creating and managing agents, calls and knowledge bases, custom action nodes that call external APIs mid-call, and an MCP server that connects Cursor, Claude, Codex and other MCP-capable clients

Integrations

• HubSpot
• Salesforce
• Zapier
• Cal.com
• GoHighLevel
• Twilio
• Genesys
• Avaya
• Five9
• Cisco
• RingCentral

Deployment and Support

Deployment

• Cloud (SaaS)
• Browser-based

Support

• Email helpdesk

Onboarding

• Documentation and knowledge base
• Personal consulting

Company size

• Enterprise

Suitability

The table combines the industries the vendor addresses with the company sizes the tool is aimed at. An empty cell means the combination is not stated, not that it is ruled out.

Pros and Cons

Pricing

• Enterprise

  $30,000

  Per year, the stated starting point. Scoped around call volume, concurrency, telephony setup, integrations and security needs, and covers implementation, onboarding, testing, training, launch support and ongoing optimisation, with SLA and support terms set in the contract.

Best For

• Technology

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