Registry — 20 transports · verified 2026-09-25 # Transports The pipe, not the endpoint. A transport is the channel or wire format an agent's bytes travel over — MCP and A2A between software, Slack and email between people, SSH and mesh VPNs into machines, PSTN and WebRTC for voice. Integrations tell you what an agent connects to; transports tell you how the conversation physically moves. T.01 ## Agent wire protocols — Wire formats between agents, hosts, and tool servers [## A2A (Agent2Agent) Cross-vendor agent wire: Agent Cards for discovery, task lifecycle and streaming updates. Google-originated, now Linux Foundation. 05 agents →](https://www.agentlist.io/transports/a2a) [## ACP Two lineages share the acronym: Zed's Agent Client Protocol (editor↔agent, JSON-RPC — how JetBrains/VS Code embed terminal agents) and IBM's earlier Agent Communication Protocol, now folded into A2A. 06 agents →](https://www.agentlist.io/transports/acp) [## AG-UI CopilotKit's event protocol between an agent backend and a frontend — streaming state, tool calls, and human-in-the-loop checkpoints. —](https://www.agentlist.io/transports/ag-ui) [## AGNTCY / SLIM Cisco-originated 'Internet of Agents' stack — agent directory plus the SLIM secure messaging fabric and identity badges. 01 agents →](https://www.agentlist.io/transports/agntcy-slim) [## AITP NEAR's Agent Interaction & Transaction Protocol — capability negotiation and payments between agents, still early. —](https://www.agentlist.io/transports/aitp) [## ANP (Agent Network Protocol) Decentralized agent web — DID-based identity, capability description, and peer-to-peer messaging with no central directory. 01 agents →](https://www.agentlist.io/transports/anp) [## MCP (Model Context Protocol) JSON-RPC tool and context wire between an agent runtime and tool servers — stdio or streamable HTTP. 35 agents →](https://www.agentlist.io/transports/mcp) T.02 ## Messaging channels — Human-facing chat and mail channels agents speak [## Discord Gateway websocket plus slash commands — community servers double as agent control rooms. 05 agents →](https://www.agentlist.io/transports/discord) [## Email (SMTP/IMAP) The oldest interoperable messaging transport — agents get an address, parse threads, and reply over SMTP/IMAP. 15 agents →](https://www.agentlist.io/transports/email) [## iMessage macOS-only bridges drive Messages.app — no official API, so agents piggyback on a logged-in Mac. 01 agents →](https://www.agentlist.io/transports/imessage) [## Signal signal-cli / linked-device bridges — private-channel agents where the audience is one person. 01 agents →](https://www.agentlist.io/transports/signal) [## Slack The default enterprise channel — agents listen, reply, and post via Bolt apps or incoming webhooks. 20 agents →](https://www.agentlist.io/transports/slack) [## Telegram Bot API long-polling or webhooks — the most common channel for self-hosted personal agents. 06 agents →](https://www.agentlist.io/transports/telegram) [## WhatsApp Business Cloud API or bridged sessions — the consumer channel with the widest reach. 05 agents →](https://www.agentlist.io/transports/whatsapp) T.03 ## Remote access & reachability — How the outside world reaches a local agent [## HTTPS tunnels Cloudflare Tunnel, ngrok, Tailscale Funnel — give a localhost agent a public URL for inbound webhooks and remote control. 01 agents →](https://www.agentlist.io/transports/tunnel) [## Mesh VPN (Tailscale-class) WireGuard overlays like Tailscale, ZeroTier, NetBird — a self-hosted agent stays reachable across devices without ever touching the public internet. 04 agents →](https://www.agentlist.io/transports/mesh-vpn) [## SSH The default pipe into a remote machine — cloud agents provision SSH-reachable workspaces, and every terminal agent inherits it wherever it runs. 03 agents →](https://www.agentlist.io/transports/ssh) [## Webhooks Inbound HTTP callbacks — how external systems wake an agent up rather than the agent polling. 04 agents →](https://www.agentlist.io/transports/webhooks) T.04 ## Realtime media — Low-latency voice and media pipes [## PSTN / SIP Phone calls — telephony carriers terminate agent voice onto the public phone network. 08 agents →](https://www.agentlist.io/transports/pstn-sip) [## WebRTC Low-latency browser and app media — the transport behind in-page voice agents. 04 agents →](https://www.agentlist.io/transports/webrtc) FAQ ## Frequently asked ### What counts as a transport? The pipe, not the endpoint. A transport is the channel or wire format an agent's bytes travel over — MCP and A2A between software, Slack and email between people, SSH and mesh VPNs into machines, PSTN and WebRTC for voice. Integrations tell you what an agent connects to; transports tell you how the conversation physically moves. ### Aren't Slack and Gmail already listed under integrations? Yes — a channel can be both. As an integration, Slack is a target the agent connects to. As a transport, the Slack socket is how a human reaches the agent and how its replies get back out. The same channel appears in both registries when it plays both roles. ### Why do wire protocols matter more than model choice? Protocols outlive vendors. An agent that speaks MCP can use every MCP server ever written; one that speaks A2A can be discovered and tasked by any compliant orchestrator. The wire format determines who else the agent can talk to — swap the model and the transports still hold. ### How are transports assigned to systems? Only transports verifiable from each system's documented feature set are tagged — an MCP client or server mode, a documented Slack/Telegram channel, SSH into a provisioned workspace, telephony for voice agents. Tags are re-checked when the catalog is regenerated. --- Source: [Agent transports — the wires agents actually speak | agentlist.io](https://www.agentlist.io/transports). This is the public page rendered as Markdown; interactive controls require the website.