3CX API Patterns

Overview

3CX added a native MCP server built directly into the PBX, introduced in 3CX V20 Update 10 (announced July 30, 2026 as an Alpha release — 3CX's own release notes describe Update 10 Alpha as "intended for testing and evaluation only"). Treat everything in this plugin as based on that Alpha: exact tool names, the permissions reference, and behavior may all shift before 3CX ships Update 10 GA.

This is a different project from the older third-party SSIG-IT/3cx-mcp-server on GitHub, a community-built MCP server that talks to 3CX's REST API rather than shipping inside the PBX. Do not mix the two up, and do not carry claims from the community project into this one — in particular, its "Enterprise/Enterprise Plus license required" claim is specific to that project and is not confirmed for 3CX's native MCP server.

Anti-triggers

• The community 3cx-mcp-server project — different codebase, different tool surface, different auth model (its own API-key setup rather than per-PBX OAuth). Nothing in this plugin describes it, and nothing about it should be assumed here.
• A customer's "the phones are down" ticket — that's ticket handling in the PSA, not a 3CX MCP call. Use halopsa-tickets, connectwise-psa-tickets, or autotask-tickets to work the ticket itself; come back to this plugin once you need the PBX-side facts.
• WYRE's Conduit vendor catalog — 3CX has no catalog entry there and, structurally, cannot: Conduit's catalog vendors share one fixed endpoint per vendor, and every 3CX PBX is its own origin with its own authorization server. See Connection & Authentication below for the two ways this plugin actually reaches a PBX.

Connection & Authentication

Every PBX is its own endpoint

Unlike a hosted SaaS MCP server, there is no single 3CX MCP URL. Each PBX exposes its own endpoint at its own FQDN, following the pattern:

https://yourpbx.3cx.eu/mcp

(or whatever FQDN that customer's PBX actually uses). Transport is Streamable HTTP. A skill, command, or agent in this plugin that needs to call a tool always does so against whichever PBX endpoint the current session is already connected to — nothing here can assume a fixed URL across customers.

Admin-side setup (on the PBX)

An admin enables the connection from inside that PBX's own console:

1. Sign into the 3CX Admin Console for the target PBX.
2. Admin → Integrations → MCP Clients → Add MCP Client.
3. 3CX displays the MCP Server URL for that PBX — copy it for the client-side step below.

Client-side setup — direct connection (no gateway)

For a technician working standalone in Claude Code, with no MSP gateway in front of it:

claude mcp add --scope project --transport http 3CX "https://yourpbx.3cx.eu/mcp"
claude

Then inside Claude:

1. Run /mcp and select the 3CX server.
2. Choose Authenticate. Claude opens the 3CX authorization page in the browser.
3. Sign in, review the requested access, and select Allow.
4. Claude confirms the connection succeeded.

The new connection also then shows up in that PBX's own Admin → Integrations → MCP Clients list — the authorization is visible and revocable from both sides.

Client-side setup — through Conduit's BYO MCP feature

An MSP already using WYRE's Conduit gateway for other vendors does not need a separate direct connection per PBX. Conduit has a generic "Bring Your Own (BYO) MCP server" feature (/connect/byo) built for exactly this shape — a vendor with no fixed shared endpoint. Paste the PBX's MCP URL from the admin step above into that form; Conduit then:

1. Discovers the PBX's own OAuth authorization server at runtime — RFC 9728 protected-resource metadata, then RFC 8414 authorization-server metadata.
2. Registers a client dynamically against that authorization server (RFC 7591 DCR).
3. Runs the normal authorization-code + PKCE flow, validating the callback's iss against the discovered issuer (RFC 9207) before persisting tokens.

No 3CX-specific code exists in Conduit for this — the same generic BYO path handles any MCP server shaped this way. See Tool permission tiers under Conduit BYO below for how Conduit decides what an operator may call once connected, and this plugin's GOVERNANCE.md for the full picture.

Permission Model

Tool access is entirely inherited from the 3CX user account that approved the OAuth connection. Claude can do exactly what that account's 3CX role already permits inside 3CX — nothing more. There is no separate Claude-specific permission layer on the PBX side.

One tool is restricted regardless of role: the Query tool (see the pbx-admin skill) is hard-restricted server-side to read-only SQL SELECT statements, no matter what the connecting account is otherwise allowed to do in 3CX.

Discovering the Live Tool Surface

3CX's own "MCP Tools and Permissions Reference" documents these tools by human-readable label — find a contact by email, list active calls, drop a call, and so on — but does not publish the literal machine tool-name strings anywhere publicly accessible. The skills in this plugin describe the tool surface by capability for that reason, deliberately without inventing exact snake_case identifiers that cannot be verified against a real PBX.

Before calling a tool, confirm its real name and schema by calling the standard MCP tools/list method against the connected PBX. This is also the only reliable way to know what changed between the Update 10 Alpha and any later release — the tool surface described here is a snapshot, not a guarantee.

Tool Permission Tiers Under Conduit BYO

If a PBX is reached through Conduit's BYO path rather than a direct connection, Conduit still has to decide a permission tier for each tool it has never seen before — there is no hand-curated VENDOR_TOOL_CONFIG entry for 3CX to draw from. It does this with a name-and-description heuristic that is deliberately conservative:

• A leading verb from a fixed read-shaped set (get, list, search, find, query, and similar) tiers the tool read.
• Any other leading verb — including one the heuristic has simply never seen before — tiers the tool write. Unrecognized verbs are never silently treated as read.
• A secret/credential noun anywhere in the name or description escalates to admin, and a mutating verb on a privileged-account noun (roles, members, billing, API keys, org settings) does too.

This matters concretely for one 3CX tool: the read-only Query tool is enforced SELECT-only inside the PBX, but Conduit's heuristic tiers purely on the tool's name. If that tool's real name is built around a generic "run" or "execute" action rather than a get/list/query-style read verb, Conduit will tier it write despite the PBX-side restriction. Don't assume read for it; check the tool's actual granted tier after connecting.

Gotchas

• This is Alpha software. Exact tool names, the permissions reference, and behavior can all change before 3CX ships Update 10 GA. Re-verify against tools/list rather than trusting a cached mental model, especially months after this was written.
• No shared URL. Every other skill and command in this plugin assumes an already-connected PBX; there is nothing to hardcode across customers.
• Don't borrow tool names from the community 3cx-mcp-server project — it is a different codebase talking to a different API surface.

Related Skills

• Directory & Contacts — contact and extension lookups
• Calls, Queues & Profiles — live call/queue state and the write actions that change it
• PBX Admin & Diagnostics — system diagnostics, PBX inventory, and configuration writes