Use when working with SIP messages, methods, call flows, and protocol fundamentals for VoIP applications.
View on GitHubFebruary 5, 2026
Select agents to install to:
npx add-skill https://github.com/TheBushidoCollective/han/blob/main/plugins/specialized/sip/skills/sip-protocol-fundamentals/SKILL.md -a claude-code --skill sip-protocol-fundamentalsInstallation paths:
.claude/skills/sip-protocol-fundamentals/# SIP Protocol Fundamentals Master the Session Initiation Protocol (SIP) for building VoIP applications, understanding SIP messages, methods, and call flows essential for real-time communications. ## Understanding SIP SIP is an application-layer signaling protocol defined in RFC 3261 for creating, modifying, and terminating sessions with one or more participants. ## SIP Message Structure ``` INVITE sip:bob@biloxi.com SIP/2.0 Via: SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob <sip:bob@biloxi.com> From: Alice <sip:alice@atlanta.com>;tag=1928301774 Call-ID: a84b4c76e66710@pc33.atlanta.com CSeq: 314159 INVITE Contact: <sip:alice@pc33.atlanta.com> Content-Type: application/sdp Content-Length: 142 ``` ## When to Use This Skill Use sip-protocol-fundamentals when building VoIP applications with SIP signaling. ## Best Practices - Always include unique branch parameters in Via headers - Implement proper transaction timeout and retransmission - Handle all SIP response codes appropriately ## Common Pitfalls - Forgetting to include branch parameter in Via headers - Not implementing transaction retransmission timers - Ignoring provisional responses ## Resources - [RFC 3261 - SIP](https://tools.ietf.org/html/rfc3261) - [PJSIP](https://www.pjsip.org/)