utilpeek: Check whether a company is registered on the Peppol e-invoicing network. Returns whether a Peppol participant ID (such as 0192:983887457) is registered on the Peppol e-invoicing network, from its SML DNS record; if so, its SMP URL and the document types the SMP lists (BIS Billing 3.0 invoice and credit note, order, despatch advice and invoice response labelled; others raw). Input: participant, optional scheme. A DNS registration only shows the participant is reachable on Peppol, not that the company is verified. If the SMP cannot be read the DNS answer is still returned with smp_error. Bad IDs are a 422 and a DNS outage a 503 (neither charged). Typically 0.2-2 s. Price: USD 0.002. Free: 10 utilpeek calls per IP per UTC day. Docs: https://tanod.dev/learn/peppol-participant-lookup-api.html