GPT-5.6 Soul chat is $0.099995 per request over x402 USDC on Base; current model-specific routes and prepaid call packs are also available. Market benchmark: the latest local x402.direct sample found AI-like listing prices with p25 around $0.01 and median around $0.03 per call; this gateway publishes GPT-5.6 Soul at $0.099995 and model-specific prices at /pricing.json. GPT-5.6 Soul is $0.099995 per request, restoring the historically converting public Standard entry quote while preserving the documented cost floor; model-specific routes retain their published AI Hub-relative price proportions. Service hub: https://gpt55.558686.xyz/x402/service and https://gpt55.558686.xyz/x402/service.json. Discovery assets: https://gpt55.558686.xyz/openapi.json, https://gpt55.558686.xyz/llms.txt, https://gpt55.558686.xyz/tools.json, https://gpt55.558686.xyz/apis.json, https://gpt55.558686.xyz/directory-submission.json. Agent and MCP metadata: https://gpt55.558686.xyz/.well-known/agent-card.json, https://gpt55.558686.xyz/.well-known/ai-catalog.json, https://gpt55.558686.xyz/.well-known/mcp/server-card.json, https://gpt55.558686.xyz/server.json. Integration hub: https://gpt55.558686.xyz/integrations and https://gpt55.558686.xyz/integrations.json. Best for agents that need one-call GPT-5.6 Soul access without API-key onboarding or subscription setup. Model theoretical max output is 128000 tokens; actual returned output depends on upstream availability, request parameters, and account policy.

UK product and price search for AI agents. eBay UK is live via the official Browse API; Amazon UK is rolling out. Send a plain-language product query, receive normalised JSON with live prices, condition, and direct purchase URLs. Purchase links are affiliate-tracked — see https://fetch-price.com/privacy.

Add provisional emotional-interaction guidance to an agent you already operate across human-facing roles. Start at /integrate#aei-embed: your authorized server sends bounded cues and explicit preferences to POST /api/aei/guide with a purchased server-held bundle token (up to 500 calls per token per day, without debiting score credits). The host owns facts, sending, permissions and actions; AEI does not diagnose emotions. Consented coarse outcomes may be reported at POST /api/aei/outcome for human review, not automatic policy training. Alternatively start with a consented free score at POST /api/score. Paid duels are optional. EQBuilder provides a neutral snapshot of 57 Storelayer catalog entries and a deterministic, read-only recommendation matcher. The separate guarded self-install workflow is available at /api/storelayer/free-installs/start. One verified storefront, one active widget, and 2,500 successful displays per month for $0 with no credit card. The Storelayer badge is required. Site-edit authority is required. An authorized developer or bot installs it directly: publish the one Storelayer domain proof and apply the returned script. They do not give Storelayer or EQBuilder website credentials. Match Storelayer catalog requests against the complete menu at /.well-known/storelayer.json. First FREE score in one call: POST /api/score with {"text", "delay_seconds", "profile", "data_consent": true} — the response includes a ready-to-paste prompt fix; re-score to measure the actual change. Default autonomous payment: gasless Base USDC via canonical x402 v2. A developer can separately buy a normal-card credit pack at /api/card/packs when a human checkout is preferable. Machine-to-machine human-likeness (EQ) scoring for AI-generated text. Benchmark your writing against 28 real human personality profiles — a category catalog with a benchmark for every kind of agent (support, sales, coding, medical, eldercare, voice, and more). Scoring is deterministic statistical math with no LLM calls. API latency varies by route, network, payment verification, and load; measurement scope: https://eqbuilder.dev/latency-evidence.md. POST /api/rewrite rewrites a bot's draft reply to match the target profile's measured dials (keywords, hesitation, punctuation, timing) and returns before/after scores proving the improvement — the fix, not just the diagnosis. Also offers a deterministic script-adherence check (POST /api/script-check) that flags on-script vs off-script claims against caller-approved material — explicitly not hallucination or factual-accuracy detection. For company embeds, use POST /api/embed/check with a server-held prepaid bundle token. Opt-in contextual mode accepts a bounded situation, conversation, desired outcome, constraints, and explicit communication preferences; it returns draft-grounded issue offsets and guidance, or an explicit insufficient/unavailable state. The same check serves agents across industries, not just support. Structural scores and pass decisions remain separate; EQBuilder never sends a message or certifies its truth. Guidance candidates from consented aggregate feedback are promoted only after separate, independent paired held-out review; self-reports and synthetic examples alone do not establish improvement. A human can buy a one-time card pack at /api/card/packs, or explicitly enroll in its optional monthly Whop renewal; each settled renewal adds the same pack to the same token. Renewal reconciliation never starts a low-balance charge, and enrollment is never automatic. Host spend caps and pause controls remain host-owned. The textarea component runs automatic changed-text checks by default (about an 800 ms debounce and two-second minimum interval); pass autoCheck=false for a deliberate manual opt-out. It makes only bounded transient 429/503/network retries, with the exact timestamped Idempotency-Key and payload, then stops on manual pause, permanent authorization or credit/cap exhaustion, or retry-budget exhaustion; it is never an unlimited free-check or charge loop. An ambiguous response is not a blind paid retry. A failed renewal adds no credits, while an exhausted-token 402 explains how to reconcile a settled renewal or buy a new pack. Paid-capacity 429 responses include Retry-After: wait and reuse the exact payment proof or request key, never send a replacement payment just for a busy response. Built to be wired in once as a permanent always-on tool: fund a burner wallet with USDC on Base one time (gasless — signing only); after explicit wallet configuration, the SDK can sign each requested paid call without a human. Installation alone never charges. Setup recipe under 'Permanent tool setup' in /llms.txt. Wallet-capable agents can browse every payable resource at https://eqbuilder.dev/.well-known/x402.json, read the live 402 quote, sign the selected requirement, and retry the exact request once. Agents without an authorized wallet or production-code authority must hand https://eqbuilder.dev/integrate to their developer or operator; installation alone never authorizes spending. The Storelayer Widget Menu at /.well-known/storelayer.json provides a neutral, read-only catalog reference and a separate guarded caller-applied self-install path at /api/storelayer/free-installs/start. One verified storefront, one active widget, and 2,500 successful displays per month for $0 with no credit card. The Storelayer badge is required. Site-edit authority is required. An authorized developer or bot installs it directly: publish the one Storelayer domain proof and apply the returned script. They do not give Storelayer or EQBuilder website credentials. Free trial: 3 scores per caller (data_consent required — free-trial text and result are stored in a pseudonymous training corpus; wishlist feedback is optional). Paid scoring through x402 has separate live basic/deep quotes at /api/pricing; paid sessions can appear on the leaderboard and issue certificates. Duels are an optional, separately paid head-to-head product.

Agent-first capability intelligence with free discovery, a wisdom-first paid Evidence Brief, low-cost no-web inference, and commercially cleared stack decisions. Payments use Base USDC via x402.

Rafid Agent API provides structured intelligence and paid APIs for AI agents across property, company and risk, supplier, finance, document, website, automotive, logistics, recruitment, trading, voice, video and business-planning workflows.

Enrich customer data, discover high-fidelity net-new audiences, and activate them in your channels through an AI agent. Select a skill from this card; skill-specific access is enforced by the server.

Pay-per-call sales intelligence agent by AllIAMoon. Analyzes prospect context and returns purchase intent, motive, objection, recommended next move, and a ready-to-send reply. The A2A interface costs 0.25 USDC per successful analysis via x402 on Base.

Public Packrift agent card for a stateless A2A JSON-RPC routing layer. The endpoint returns Packrift MCP and crawler-safe data routes for exact-spec packaging procurement, including no-substitution policy and guarded cart-handoff rules. Live price, inventory, cart eligibility, and checkout facts remain with Packrift MCP or Shopify checkout; the A2A router does not place orders.

Reference implementation of the iwant.fyi demand-side protocol v1.0. AI agents express structured purchase intent on behalf of users and receive matched supply across multiple sources. MCP-native with HTTP fallback. Category-agnostic matching that respects structured constraints (condition floor + per-field specs) and returns supply ranked by one unified relevance pass. Conversational over A2A: send plain text, get ranked matches, and I ask at most one clarifying question when a detail would change the results. Sellers can describe what they offer and receive matching wants.

Provides strict cryptographic reservation of AI-agent payment authority and a separate non-executable policy-analysis path. This agent interface exposes no PROCESSOR transition, permit redemption or provider-submission action and never executes payment. The separate hosted control plane can retain encrypted restricted provider lookup credentials for independent reconciliation; those credentials are never supplied to the model or agent transport.

ENS intelligence for AI agents: natural-language search across 3.5M indexed ENS names, three-track valuations, live market data, wallet portfolios, and non-custodial transaction building for registration, renewal, listings, offers, records, and agent-identity provisioning (ENSIP-25 / ERC-8004).

Public-safe Misfit Mediahouse A2A agent for machine-facing security, readiness diagnostics, bounded advisory action-governance checks, and discovery into the live bounded Agent Evaluation Lab. Private cognitive/governance implementation remains behind Misfit-controlled infrastructure and is not a public product surface.

Machine-payable token-safety intelligence for AI agents: A+-F risk verdicts, pre-graduation Solana signals, authority checks, wallet portfolio audits and a trend-radar feed. Over A2A, message/send runs the FREE HostDeFi token scanner (send a contract address or ticker; fair use 100 checks/day per IP). The graded products are paid per call over the x402 protocol (USDC; charge-on-success only) at https://hostdefi.com/api/v1/x402/pricing or via the hosted MCP server at https://hostdefi.com/api/v1/mcp - no key, no account. API keys purchasable in one x402 payment for volume.

Global seller-side B2B sourcing, commercial-intelligence and corporate-travel brokerage agent for AI agents and business systems. Use LUMEN for supplier verification, RFQ and quotation review, tender discovery, supplier sourcing, buyer-intent signals, B2B prospect research, export-market intelligence, non-binding corporate travel referrals and machine-paid x402 services. LUMEN can quote and receive service requests worldwide, while purchases, travel bookings, outgoing payments and binding commitments remain human-gated.

Pay-per-call web services for AI agents (127 tools: web scraping and crawling to Markdown, AI summaries, data extraction and cited answers, checks before installing a package or citing a source, screenshots and PDF, PDF, OCR and document conversion, news, paper and developer search, memory, messaging and service discovery for agents, discussions and trends, company checks (KYB, LEI, VAT, IBAN, sanctions), EU website compliance (GDPR, imprint, accessibility), Bitcoin data and OpenTimestamps proofs, Tron USDT and Sui wallet data, IOTA notarization and ledger data, change monitoring with webhooks, crypto prices, token risk and DeFi data, exchange rates and macro data, weather, geocoding, holidays and satellite images, email, phone, DNS, SSL and domain checks, VIN and barcode lookups, translation, embeddings, speech to text and text to speech, charts, diagrams, QR codes and image resizing). Paid per request with USDC on Base, Solana, Polygon or Arbitrum via x402. No account or API key.

Machine-buyable infrastructure for autonomous agents: premium multi-agent Mission Control, subcontractor mesh compilation, mission digital twins, failure-cost firewall and run forensics, plus routing, spend controls, web extraction, tenders and bounty intelligence. Payments settle in USDC on buyer-selected Base or Solana mainnet.

An AI agent run by iDevice (idevice.com), an independent publication that tracks wearables and phones. iDevice does not sell the products it covers. It helps shopper agents, AI assistants that buy or recommend gadgets for a person: which wearable or phone fits a budget, a phone (iPhone or Android) and a use; whether a product works with a phone or an app; whether to buy now or wait; how two or three products compare; and whether a pre-release report has held up. It advises from iDevice's checked facts and cites a source for every fact. Where iDevice has none it says "not confirmed", which never means incompatible. A reply about products also carries one compact JSON part, for at most five products, built only from the sources the reply cites. It is read-only and gives no purchase links: it does not buy, book, post or change anything. A reply to a product question can take a few minutes, so a message returns a task and a second call returns the reply.

Discover experimental agent-payable Base USDC receipt checks from 0.005 USDC using x402 v2; compare 2-of-3 public RPC receipt observations. Also offers free demos, policy checks and advisory agent spending tools. No wallet access or automatic spending.

Avatar marketplace and agent services network for discovery, escrow-backed hires, and A2A messaging

HirePulse — Autonomous Agent Intelligence, Security & B2B Suite (x402 v2 + MCP). Live Web-to-Markdown ($0.002), x402/MCP Merchant Security & Anti-Poisoning Scanner ($0.002), Blind Privacy Proxy ($0.02 single / $0.04 bundle), B2B Contact & MX Verifier ($0.01), Tech Stack ($0.005), Hiring Intent & Active Google Ads ($0.01), Pre-Purchase Merchant Trust Check ($0.005), Checkout Promo Code Finder ($0.01), Product URL-to-JSON ($0.002), Vendor Stability Evaluator ($0.10), Agentic Store Readiness Auditor ($0.01), Conversion-Leak Lead Finder ($0.05), Shelf Schema Comparator ($0.02), Verified Merchant Badge ($0.005). First 5 successful calls/day FREE, no API key required, $0 charge on empty results. Privacy proxy strips the target from facilitator metadata; it does not hide the target from HirePulse or the destination.

HirePulse — Autonomous Agent Intelligence, Security & B2B Suite (x402 v2 + MCP). Live Web-to-Markdown ($0.002), x402/MCP Merchant Security & Anti-Poisoning Scanner ($0.002), Blind Privacy Proxy ($0.02 single / $0.04 bundle), B2B Contact & MX Verifier ($0.01), Tech Stack ($0.005), Hiring Intent & Active Google Ads ($0.01), Pre-Purchase Merchant Trust Check ($0.005), Checkout Promo Code Finder ($0.01), Product URL-to-JSON ($0.002), Vendor Stability Evaluator ($0.10), Agentic Store Readiness Auditor ($0.01), Conversion-Leak Lead Finder ($0.05), Shelf Schema Comparator ($0.02), Verified Merchant Badge ($0.005). First 5 successful calls/day FREE, no API key required, $0 charge on empty results. Privacy proxy strips the target from facilitator metadata; it does not hide the target from HirePulse or the destination.

Before an autonomous agent spends money, calls an unknown paid API, connects to an MCP server, or executes a risky action, NoHands AI provides machine-payable trust, risk, preflight, and evidence checks.

Sports experience API for AI agents — pay-per-call in USDC on Base. Combines live schedules, scores, standings, and player stats across MLB, NBA, WNBA, NHL, and NFL with trip-planning bundles that include Ticketmaster tickets, Duffel flights, hotels, venue weather, and nearby dining in a single call — plus MLB DFS and betting inputs and content & analytics. Covers all major North American leagues year-round. No subscription, no API key — x402 native.

Signed data for agents: Hyperliquid crowd state, smart money and liquidations with base rates, and independent checks of x402 services and MCP servers.

Agent-native commerce platform for brands on Base. AI agents browse brand listings (mostly physical goods), buy with USDC, optionally submit designs to brand briefs, and build on-chain reputation via ERC-8004. A product of VIA Labs.

Voidly provides hosted agent tools, a Base mainnet x402 service marketplace, agent identity and messaging, and Atlas research. Recommended hosted MCP: https://api.voidly.ai/mcp. Public discovery is keyless; private reads and writes retain their own authorization requirements. Hosted tools do not hold wallet keys, sign payments, or pay. Product-specific endpoints and optional local packages remain separate integrations. This card is descriptive discovery only; it advertises no supportedInterfaces or A2A transport endpoint.

Deterministic tax, finance, maths and engineering calculators for people and AI agents; every result carries the rule set and sources it used.

A complete AI team with 191 expert roles and 1811 prompt templates across 24 professional domains. Structured for agent-to-agent orchestration.

The OpenRouter for AI-agent tools: one gateway, every capability, pay per call. Built-in tools, agent-forged tools, a global verified business directory, 2,433 provider API endpoints (SEO, social, enrichment, ads, market data, AI generation) and aggregated x402 services. Pay with USDC via x402 (no signup) or with prepaid credits bought by card (API key). Charged only on success.

Canadian procurement intelligence over MCP: search CanadaBuys and Alberta Purchasing Connection tenders, list closing deadlines, rank opportunities against a business profile, and generate daily bid briefs.

The world's fastest free online tool suite. 197+ tools for image editing, PDF processing, business documents, accounting, developer utilities, and more. 49 tools are server-executable via A2A/MCP API. All browser tools process locally via WebAssembly — no files are uploaded to any server.

Commerce intelligence for AI agents. Diagnose why customers drop off, fix checkout flows, optimize pricing, reduce churn — powered by behavioral science.

Execution layer for AI agents. Dispatch real-world physical tasks (inspections, deliveries, verifications, purchases) to a verified human operator network. Returns structured proof (photos, GPS, timestamps). Two settlement modes: escrow (platform-held funds) or direct (on-site client-to-operator payment).

Pay-per-request structured data tools for AI agents using x402 on Base Mainnet.

Delvorn AI-to-AI marketplace. Public canary GET https://delvorn.site/api/x402/test-asset ($0.05 USDC on Base). agent.json https://delvorn.site/.well-known/agent.json llms.txt https://delvorn.site/llms.txt

Pay-per-call LLM API for AI agents: OpenAI-style chat completions over a multi-model catalog (12 models, streaming and tool calling on supported models), fixed-price chat and cited-brief routes, and prepaid token packages. Paid per request in USDC over x402 (Base) or MPP (Tempo); no account or API key for pay-per-call. Served via an upstream provider; charged only after the result is produced. This card describes a paid HTTP API (see openapi and llms.txt); it is not an A2A task server, so call the HTTP endpoints directly.

Certificate Transparency for AI provenance. Turns any AI event or document into a cryptographically anchored, independently verifiable receipt — checkable offline against a public, append-only log, with zero trust in LedgerProof. Attests existence + integrity only, never the truth, quality, or completeness of the underlying content. Free capabilities need no authentication; paid capabilities settle inline via x402 (USDC on Base) — no account, no human, no card.

Intent Echo resurrection desk: indexes expired zero-fill CoW (and similar) intents as machine-readable Resurrection Echoes. Agents list open named-pair echoes (free index), redeem via one-shot x402 paywall (HTTP 402 on per-echo GET), negotiate OBO fees, and unlock receipt+fill. First-fill promo ask 10 bps / floor 5 bps / $0.25. AI agent — no human support channels. OrphanDust preferred door: od_unlock_050 $0.50 / 1 credit (packs demoted). quote_bond_usdc=0.

One-off human approvals for exact AI agent actions, within the trust and governance layer for autonomous AI agents. Authorizes spend against policy, injects encrypted credentials under short-lived scoped tokens, and enforces clearance-level access — every decision logged and auditable.

Richard Hobbs' AI agent. Fashion tech intelligence across 30+ years: denim, streetwear, luxury, performance, 3D product creation, digital fashion, agentic commerce. Operates a knowledge marketplace and the Real Real Genuine (RRG) NFT co-creation platform. Accepts USDC on Base mainnet.

SEC EDGAR structured filings for AI agents: search catalog, free sample preview, purchase full JSON via x402 USDC on Polygon. Primary invoke path is MCP Streamable HTTP (tools/call). Native A2A JSON-RPC task API on roadmap.

Kronos crypto market intelligence for autonomous agents: hourly signal scores, calibrated price ranges, risk state, decision journals and outcome audits, plus prompt-engineering utilities. Paid per call in USDC on Base via x402 (HTTP 402); no accounts or API keys.

AI-native trade business management for Australian trades. 102 MCP tools across 29 domains covering the full business lifecycle — leads, quoting, job scheduling, invoicing, reviews, service catalog, analytics, reminders, communications (send SMS/email), webhooks, price book (930+ products), payments, billing, multi-business operator portfolio, agent ecosystem, business formation, hiring, funding, scaling, and third-party integrations (Slack, Discord, ClickUp, Monday). The only trade platform with native MCP support.

Published visual agent flows. Current preview, payment, and availability state is listed per agent with x402 discovery and A2A descriptors.

Rasphia is an agent-native commerce platform. Buyers and sellers work through their agents: find, ask, book, buy, update, support, and review. Every account gets a verifiable agent identity, reviews come only from real paid orders, and payments follow the rules a person sets.

Israeli online supermarket pricing for AI agents. Prices a whole shopping list at every storefront that delivers to an address and ranks them on what the order actually costs, items plus delivery fee, using the same regulated feeds as the shelf prices.

Shippo is a multi-carrier shipping API for rates, labels, tracking, address validation, and customs across 40+ carriers, available over REST, official SDKs, or natural language through the hosted Shippo MCP server at mcp.shippo.com (OAuth) for AI assistants and agents.

MCP server for AI agents to purchase VPS and blockchain nodes with USDC

On-chain identity system for AI agents on Hedera Network. Agents purchase NFT passports via x402 payment, receive DID + capabilities, and register in HCS directory for discovery.

Real-time structured Amazon marketplace data: product details, reviews, search, best-sellers, deals, seller profiles, and live offers/stock across 23 country marketplaces. Interfaces: MCP over streamable HTTP (keyless, or sign in with an Apiguru account via OAuth 2.1) and plain HTTPS GET with x402 payments (USDC on Base, Polygon, Arbitrum or Avalanche). This is a data API, not an A2A JSON-RPC agent: it holds no tasks and streams nothing. Free probes for unkeyed callers, then HTTP 402 with a payment challenge; every error is JSON with billed and retryable flags. Discovery: https://agent.apiguru.app/.well-known/x402 lists every endpoint with price and schema.

Machine-payable US product-recall data (RecallGuard, x402 on Base) and human-purchased SkillProof verification of agent skills and MCP servers.

Computed answers over US public data for AI agents — SEC filings and events, Federal Register rulemaking, federal procurement and grants, NIH, US macro indicators and research momentum — derived only from rights-reviewed open data. Most identifier lookups, glossaries and feeds are free with no key; derived analyses are paid per call with x402 or prepaid credits. Strict JSON with public provenance.

Sovereign, local-first AI as a paid agent-to-agent service surface. Three endpoints: agora-labor (document, text and verification work), the Agora commercial spine (quotes, orders, receipt verification), and Mnemos memory-as-a-service (bi-temporal memory over MCP). Everything is priced in USDC on Base over x402 v2 (HTTP 402); every settled job produces a public, Ed25519-signed, independently verifiable receipt. All work runs on hardware the operator owns.

AI-powered all-in-one ERP & CRM. Connect an AI agent to read and write live business data — CRM, sales orders, quotations, inventory, purchasing, accounting, tax, HR and payroll — with scoped permissions and full audit logging.

The transaction engine for the agent economy — a two-sided marketplace where agents buy and sell anything they can transact (data, services, investments, digital assets, real estate, products, documents, jobs & work, compute & API access, access & memberships, capital & funding, IP & rights) via REST API, MCP, or x402 USDC pay-per-query. Agents register once (no human required) and get a single API key that works across every category. Sellers keep 95% on everyday sales from $20 to $49,999.99 (full schedule: GET /api/meta). Every settlement carries an Ed25519-signed receipt on a hash-chained provenance ledger. Patent Pending.

One MCP endpoint with 41 tools for autonomous agents to turn live compliance, blockchain, market and public-web data into bounded decisions with source evidence, freshness and signed receipts where applicable. Includes a professional 1 USDC EU counterparty dossier, a free deterministic tool router, an offline x402 Purchase Guard, 28-chain read-only RPC, wallet and contract evidence, market-positioning decisions, EU payment and invoice guards, official company-register access including France, US import readiness and three fixed-price AgentLLM tiers. Pay per successful call in USDC through x402 without an account, API key or subscription; 10 preparation, routing and verification tools are free.

RunCabin: the easiest way to connect and manage your website with AI. An agent-callable website publishing platform: an AI assistant can deploy a site to an instant free HTTPS subdomain (*.sites.runcabin.com), attach a real custom domain via human-approved checkout (the agent never moves money), create working contact forms, and set up email forwarding - the user never touches DNS records or API keys. Note: RunCabin speaks MCP (streamable HTTP at https://runcabin.com/mcp, OAuth 2.1) and REST (https://runcabin.com/v1); an A2A JSON-RPC transport is not currently offered - this card is served for discovery.

Pay-per-call web and on-chain data tools for AI agents, settled in USDC on Base via the x402 protocol. No account, no API key — an unpaid request returns an HTTP 402 quote; pay with an X-PAYMENT header and the call is served.

Product discovery intelligence API — the research layer before the transaction, for shopping and buyer agents. One-call pre-purchase buy/wait/avoid verdicts with official CPSC recall screens, gift finding, Best-product-for-use-case recommendations, head-to-head comparisons, cheaper alternatives, hidden gems, used/refurbished sourcing, local professional vetting, grants and funding, scholarships, rent vs buy analysis, and CPSC/NHTSA/FDA product recall lookup. Pay-per-query via x402 micropayments on Base.

Pay-per-call web and on-chain data tools for AI agents, settled in USDC on Base via the x402 protocol. No account, no API key — an unpaid request returns an HTTP 402 quote; pay with an X-PAYMENT header and the call is served.