SignalWire

⚠️ AVOID Deprecated APIs

SignalWire maintains compatibility APIs (LAML/CXML) that should NOT be used for new development:

• LAML endpoints (/laml/) → Use REST API (/api/calling/, /api/video/)
• CXML (XML markup) → Use SWML (YAML/JSON)

This skill documents ONLY modern APIs: REST with JSON, SWML, Relay SDK, AI Agents SDK.

SignalWire Technologies Quick Reference

Technology	Use When	Format/Protocol
REST APIs	Trigger actions from backend, query state	HTTP + JSON
SWML	Define call flows, IVR, AI interactions	YAML/JSON documents
Relay SDK	Real-time WebSocket control	JavaScript/Python
AI Agents SDK	Build voice AI agents	Python decorators
Call Fabric	Route between subscribers/resources	WebSocket framework
SWAIG	AI agent calls server-side functions	HTTP POST to your endpoint

Practical Knowledge from Production

This skill combines technical API documentation with practical implementation guidance from real-world SignalWire deployments. Each workflow file includes:

• Best Practices - Production-tested techniques and patterns
• Common Patterns - Real-world implementation examples
• Anti-Patterns - What NOT to do, mistakes to avoid
• Production Tips - Deployment, monitoring, and testing insights
• Real-World Examples - Complete working patterns from live applications

These insights come from analysis of 89 SignalWire training videos, LiveWire sessions, and production deployments.

Workflows by Use Case

Getting Started:

• Authentication & Setup | Number Management

Voice Calls:

• Outbound Calling | Inbound Handling | Call Control

AI Voice Agents: Start with Voice AI overview

• SDK: Basics | Prompting | Functions | Deployment
• Best Practices: Patterns | Error Handling | Security | Testing | Debug Webhooks

Other:

• Messaging | Video | Fabric & Relay | Webhooks & Events

Quick Start Patterns

Authentication: HTTP Basic Auth with Project ID (username) + API Token (password)

Space URL: All API requests go to https://{space-name}.signalwire.com

SWML Variables: %{call.from}, %{call.to}, %{params.custom_field}, %{args.user_input}

Webhooks: HTTP POST with JSON (call_id, call_state, from, to, direction)

Errors: REST returns HTTP status + JSON with error/message. SWML logs to Dashboard.

Key Concepts

Call States: queued → created → ringing → answered → ended

SWML Sections: main (required entry point) | execute (call + return) | transfer (goto)

Resources: Subscribers, AI Agents, SWML Scripts, Video Rooms, SIP Gateways, Relay Apps (created via Dashboard or REST API)

Critical Pattern: Loop Protection

SWML gather/prompt nodes can infinite loop. Always add counters:

- set:
    loop_counter: "{{loop_counter | default(0) | int + 1}}"
- condition:
    if: "{{loop_counter}} > 3"
    then: hangup  # Prevent caller stuck in loop

For complete patterns, see Inbound Call Handling.

AI Agents SDK Reference

IMPORTANT: For AI agent tasks, start with Voice AI - it covers 90% of use cases with examples and best practices.

Only load reference docs for: Complete API parameters, advanced features (Contexts/Steps, Prefabs), platform-specific deployment (Lambda/GCF/Azure), or debugging production issues.

See Voice AI workflow "When to Pull Additional Documentation" section for detailed guidance on when to use each reference document.

Finding the Right Workflow

New to SignalWire? → Authentication & Setup

Building AI voice agent? → Voice AI

Making/receiving calls? → Outbound Calling or Inbound Handling

Debugging webhooks/callbacks? → Webhooks & Events

Need real-time control? → Fabric & Relay

Additional Resources

• Main Documentation: https://developer.signalwire.com/
• GitHub Examples: https://github.com/signalwire
• AI Agents SDK: https://github.com/signalwire/signalwire-agents
• Dashboard: https://{your-space-name}.signalwire.com