What is a voice MCP provider and why does my AI agent need one?
MCP (Model Context Protocol) is an open standard for connecting AI agents to external tools — databases, search, file systems. A voice MCP provider adds telephony to that toolset: your agent can place a call, send an SMS, or schedule a callback through a single tool invocation. Stexa is the first voice MCP provider with native Russian-language support and FZ-152 compliance (as of May 2026). Out of 9,400+ MCP servers in Smithery + mcp.so registries, none target Russian-language telephony at this depth.
How much does it cost? Is there a free tier?
7 days free, no credit card — 100 voice minutes + 50 tool calls. After that, the Start plan is ₽2,990/mo (~$32) for 500 minutes and 1 number; Business is ₽7,990/mo (~$85) for 2,000 minutes and up to 3 numbers. Additional minutes: ₽4/min (~$0.04). All MCP tools and the API key are available on every tier including trial. No sales call, no document exchange — sign up and go.
What's the latency from tool call to the customer hearing the dial tone?
400-600 ms from JSON-RPC request received to actual dial on Asterisk — significantly lower than the 2-4 seconds typical of REST voice APIs. We achieve this through a direct MCP → Asterisk ARI bridge with no intermediate REST queue. If your LLM is mid-conversation, the agent can narrate ("hold on, dialing now…") while the call initiates — the customer never hears silence.
How does the OAuth flow work for new clients?
We implement OAuth 2.1 with PKCE plus RFC 7591 Dynamic Client Registration. Your AI agent (Claude Desktop, Cursor, n8n, custom) POSTs to /mcp/v1/oauth/register with a client_name and redirect_uri — gets back a client_id and client_secret. Then a standard PKCE-protected authorization code flow exchanges the user consent for an access token. Discovery via /.well-known/oauth-authorization-server (RFC 8414) and /.well-known/oauth-protected-resource (RFC 9728).
What about data security and compliance?
Per-tenant Bearer tokens (rotatable in dashboard) plus OAuth 2.1 scopes for granular access. All traffic over TLS 1.3. Servers are hosted in Russia (Yandex Cloud Moscow). For PDP compliance under Russian federal law FZ-152, a data processing agreement is signed on Business tier and above. Every outbound call announces the recording consent and captures the customer's response — stored 3 years as a legal artifact. We do not store call audio outside Russia under any circumstance.
Which LLM providers are supported?
Stexa Voice MCP is the server side of the transport. The client can be any MCP-aware LLM: Claude (Anthropic), GPT-4/5 (OpenAI), YandexGPT, GigaChat, local models via LM Studio. Stexa internally uses YandexGPT Pro to understand the customer's speech during the call (98% accuracy on Russian), but when you use the MCP channel, LLM orchestration remains on your side — we only execute the tool invocations: make_call, send_sms, etc.
How is this different from Twilio or Vonage REST APIs?
Twilio / Vonage follow a REST + webhook model: you write a backend, register a webhook URL, Twilio POSTs JSON on each event, you respond with TwiML. That requires backend infrastructure and does not integrate directly into an LLM agent. Stexa's MCP model: your AI agent itself is the client, no backend between it and telephony. In Claude Desktop you add one line to config.json and the LLM gets the make_call tool in its context. No webhook server. For AI agents this is an on-ramp without code.