Patter: developer tool for Hermes Agent

Open-source voice AI SDK that gives an agent a phone number, with an installable skills bundle

What Patter does

You write the agent and Patter handles the path between it and the phone network. The README lists LLM options such as OpenAI, Anthropic, Google Gemini, Groq and Cerebras, plus speech-to-text and text-to-speech providers, realtime engines, and the carriers Twilio, Telnyx and Plivo. Each layer can be swapped with one line, and the SDK offers Realtime, Pipeline and Hybrid modes.

Patter runs locally with a built-in tunnel and dashboard, or simulates a call from the terminal with no phone. It includes an LLM fallback chain, tools, call transfer and guardrails, and OpenTelemetry traces of each call. For coding agents, a separate PatterAI/skills repository installs with npx skills add patterai/skills and, per the README, works in about 55 agent harnesses that consume the Agent Skills standard, with Hermes named as one.

Key features

Same API in Python and TypeScript
Swappable LLM, speech-to-text, text-to-speech, realtime and carrier providers
Realtime, Pipeline and Hybrid voice modes
Automatic LLM fallback chain, call transfer, tools and guardrails
Local tunnel and dashboard, plus call simulation from the terminal
Skills bundle for coding agents, installed with npx skills add patterai/skills

When to use it

Giving an agent a phone number so it can act as a receptionist
Teaching Hermes Agent to write Patter voice-agent code by installing the skills bundle
Switching telephony carrier from Twilio to Telnyx or Plivo by changing one line

Who it is for: Developers who want to build their own voice agents on an open-source stack instead of a hosted voice platform.

How it fits with Hermes Agent

The repository carries the hermes-agent topic, and its skills bundle is documented as usable with Hermes among about 55 agent harnesses. The SDK itself is not specific to Hermes Agent.

How to install Patter

These commands are copied from the project's README. Check the repository for the latest steps before you run them.

pip install getpatter
npm install getpatter
npx skills add patterai/skills

Requirements: Python or Node.js; provider and carrier credentials read from environment variables such as TWILIO_ACCOUNT_SID and OPENAI_API_KEY

Note: Placing real calls needs an account with a telephony carrier such as Twilio, Telnyx or Plivo plus credentials for the chosen model providers.

FAQ

What is Patter?

Patter is an open-source SDK, available for Python and TypeScript, that gives an AI agent a phone number. It runs the agent loop, speech-to-text, text-to-speech and the connection to a telephony carrier.

Does Patter work with Hermes Agent?

Patter is not a Hermes plugin, but its skills bundle can be installed into Hermes and other agents so they learn the SDK. The README names Hermes among the agents the bundle supports.

How do I install Patter?

Run pip install getpatter for Python or npm install getpatter for TypeScript. To teach a coding agent the SDK, run npx skills add patterai/skills.