MCP Server
SIP and VoIP tools
inside your AI editor
A hosted Model Context Protocol server for people who debug calls. Claude, Cursor, VS Code or Codex gets eleven SIP tools: response codes, headers, SDP offer/answer checks, call-flow ladders, E.164 and STIR/SHAKEN decoding, and the SIPSymposium AI analysis — called while you work on the trace, the config or the ticket.
mcp.json · any client
{
"mcpServers": {
"sipsymposium": { "url": "https://sipsymposium.com/mcp" }
}
}
One URL · nothing to install · free tools need no account · Streamable HTTP
What the assistant can call
Eleven tools. Ten are free.
The deterministic tools run on the server without any AI model and return structured results the assistant reasons over. The one AI tool is the full SIPSymposium analysis, behind your Pro or Teams key.
| Tool | What it returns | Cost |
|---|---|---|
lookup_sip_response_code | Reason phrase, class, what the code usually means in a real trace, link to the matching guide. | Free |
lookup_sip_header | Compact form, defining RFC, and what the header is used for when debugging. Accepts v, f, t, i, m… | Free |
parse_sip_message | Start line, canonical headers, body, parsed SDP, and lint warnings: missing mandatory headers, branch cookie, CSeq mismatch, RFC 1918 Contact or c=, Content-Length. | Free |
diff_sip_messages | Header-by-header diff of two messages — what an SBC rewrote between ingress and egress — plus an SDP comparison when both carry one. | Free |
parse_sdp | Session and media sections: codecs, ptime, direction, SRTP suites, DTLS fingerprint and setup, ICE, rtcp-mux, telephone-event, effective connection address. | Free |
compare_sdp_offer_answer | Severity-ranked offer/answer issues: rejected media, no common codec, answer-only codecs, direction pairing, ptime asymmetry, AVP vs SAVP, crypto suite, DTMF payload type, private addresses. Also a web tool. | Free |
render_sip_ladder | A Mermaid sequenceDiagram per Call-ID from any raw trace, with lanes from capture framing or Via/Request-URI. | Free |
validate_e164_number | Country code and region, national number, NANP NPA/NXX split, flags for toll-free, premium, N11, Caribbean NPAs and 555 ranges. | Free |
decode_stir_shaken_identity | Decoded PASSporT: attestation level and meaning, orig, dest, iat, origid, certificate URL, structural findings. Decodes and lints; does not verify the signature. Also a web tool. | Free |
search_sipsymposium_guides | Titles, URLs and summaries from the 83-guide library and tool pages. | Free |
analyze_sip_trace | The SIPSymposium AI analysis: severity-ranked findings with evidence, root cause and recommendations across signaling, SDP/media, NAT and encryption. Narrative mode by default. | Pro · Teams |
In practice
Ask in plain language. Get the protocol answer.
The assistant picks the tool. A pasted INVITE and 200 OK become an offer/answer check; a pasted trace becomes a ladder; a response code in a ticket becomes a reference lookup.
You, in the editor
“Here’s the INVITE and the 200 OK from the Teams Direct Routing leg. DTMF stopped working after the SBC upgrade. What changed?”
compare_sdp_offer_answer → result
warning m-line 0: telephone-event payload type 101 offered vs 100 answered — asymmetric dynamic PT; DTMF may be lost on strict stacks (RFC 4733 §2.1). warning m-line 0: ptime 20ms offered vs 30ms answered. ok common codecs: PCMA/8000, PCMU/8000
Setup
Connect your client
Every client takes the same entry. Add the headers block only if you want
analyze_sip_trace; the other ten work without it.
Claude DesktopSettings → Connectors
# Settings → Connectors → Add custom connector Name: SIPSymposium URL: https://sipsymposium.com/mcp # for analyze_sip_trace, pass the key as the api_key # argument, or bridge with a header via mcp-remote: { "mcpServers": { "sipsymposium": { "command": "npx", "args": [ "-y", "mcp-remote", "https://sipsymposium.com/mcp", "--header", "Authorization: Bearer sips_YOUR_KEY" ] } } }
Claude Codeterminal
claude mcp add --transport http sipsymposium https://sipsymposium.com/mcp
# with a key for analyze_sip_trace:
claude mcp add --transport http sipsymposium https://sipsymposium.com/mcp --header "Authorization: Bearer sips_YOUR_KEY"
Cursor~/.cursor/mcp.json
{
"mcpServers": {
"sipsymposium": { "url": "https://sipsymposium.com/mcp" }
}
}
VS Code.vscode/mcp.json
{
"servers": {
"sipsymposium": { "type": "http", "url": "https://sipsymposium.com/mcp" }
}
}
Codex CLI~/.codex/config.toml
[mcp_servers.sipsymposium] url = "https://sipsymposium.com/mcp"
Anything elsecurl
curl -X POST https://sipsymposium.com/mcp \
-H "Content-Type: application/json" \
-d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'
Boundaries
What leaves your machine, and what it costs
The same answer the REST API gives, stated for the MCP path.
Free tools
The text you pass is parsed on the server and the result is returned. No AI model is involved, nothing is stored, and no account is needed. Requests are capped at 512 KB and each text argument at 256 KB. Per-client rate limits apply.
AI analysis
analyze_sip_trace forwards the trace to the SIPSymposium analysis service under your key, with the same handling as the REST API: processed, not retained after the response. It counts against the daily analysis quota the key owner already has for the web analyzer and API.Keys
Keys are issued on Pro and Teams from the API Keys page, shown once, and revocable at any time. Send one as a
Bearer header in the client config or as the api_key argument. Without one the ten deterministic tools still work.FAQ
SIP MCP server questions
Clients, keys, data handling, and how this relates to the REST API.
What is a SIP MCP server?
An MCP (Model Context Protocol) server gives an AI assistant such as Claude, Cursor or VS Code
Copilot a set of callable tools. This one exposes SIP and VoIP engineering tools: response-code
and header lookup, SIP message parsing and diffing, SDP parsing and RFC 3264 offer/answer
comparison, Mermaid call-flow ladders, E.164 validation, STIR/SHAKEN Identity decoding, guide
search, and AI trace analysis. The assistant calls them while you work on a trace, a config or a ticket.
Do I need an account or API key?
No for the ten deterministic tools: add the URL and they work. Only
analyze_sip_trace,
which runs the SIPSymposium AI analysis, needs a Pro or Teams API key sent as an
Authorization: Bearer header or passed as the api_key argument. It counts
against the key owner’s daily analysis quota, the same quota as the web analyzer and REST API.
Which MCP clients are supported?
Any client that speaks MCP over Streamable HTTP: Claude Desktop, Claude Code, Cursor, VS Code
(Copilot agent mode), Codex CLI, Cline, Windsurf, Continue and others. Configuration is a single
entry pointing at
https://sipsymposium.com/mcp. There is nothing to install locally.
What happens to the SIP traces I send through the MCP server?
The deterministic tools parse the text you pass and return a result; nothing is stored and no AI
model is involved.
analyze_sip_trace sends the trace to the SIPSymposium analysis
service under your API key, with the same handling as the REST API: traces are processed and not
retained after the response. Requests are capped at 512 KB and each text argument at 256 KB.
How is this different from the SIPSymposium REST API?
The REST API is one endpoint for programmatic AI analysis, built for pipelines
and monitoring. The MCP server is for interactive work inside an AI assistant: it adds ten deterministic
SIP/SDP utilities that cost nothing and need no key, and wraps the same AI analysis as a tool the
assistant can call when it decides a full analysis is warranted.
Add it and ask about the next 488.
One line in your client config. The free tools answer immediately; the AI analysis is there when you want the whole story.