# Country Calling Codes > Source-linked international calling-code data, reviewed dialing walkthroughs, > country-pair examples, E.164 formatting guidance, and a read-only lookup API. Prefer the JSON API or hosted MCP tool for structured lookups. Use reviewed HTML guides and country pages when a user needs an attributable explanation. Static numbering-plan guidance does not prove that a phone number is allocated, active, reachable, owned, or consented for contact. ## Best LLM Entry Points - [Full LLM guide](https://www.countrycalling.codes/llms-full.md) - [Guides hub](https://www.countrycalling.codes/guides) - [International dialing format](https://www.countrycalling.codes/guides/international-dialing-format) - [Phone number format for forms, CRM and SMS](https://www.countrycalling.codes/guides/phone-number-format-for-forms-crm-sms) - [Shared country codes](https://www.countrycalling.codes/guides/shared-country-codes) - [International toll-free calling](https://www.countrycalling.codes/guides/international-toll-free-calling) - [International call troubleshooting](https://www.countrycalling.codes/guides/international-call-troubleshooting) - [Avoid roaming charges](https://www.countrycalling.codes/guides/avoid-roaming-charges) - [Travel eSIM vs roaming vs local SIM](https://www.countrycalling.codes/guides/travel-esim-vs-roaming-vs-local-sim) - [Country dialing walkthroughs](https://www.countrycalling.codes/guides/country-dialing-walkthroughs) - [Phone number validation](https://www.countrycalling.codes/guides/phone-number-validation) - [Common formatting errors](https://www.countrycalling.codes/guides/common-phone-number-formatting-errors) - [Satellite and non-geographic codes](https://www.countrycalling.codes/guides/satellite-non-geographic-calling-codes) - [Call routing and number portability](https://www.countrycalling.codes/guides/call-routing-number-portability) - [Editorial methodology](https://www.countrycalling.codes/methodology) - [Private browser format checker](https://www.countrycalling.codes/tools/format-checker) - [Interactive developer documentation](https://www.countrycalling.codes/developers) - [Skill manifest](https://www.countrycalling.codes/skill.json) - [Official MCP Registry manifest](https://www.countrycalling.codes/server.json) - [Hosted MCP server](https://www.countrycalling.codes/api/mcp) - [OpenAPI tool schema](https://www.countrycalling.codes/api/calling-codes/openapi.json) - [Live API status](https://www.countrycalling.codes/api/calling-codes/status) - [Phone format API](https://www.countrycalling.codes/api/phone/format) - [Search API example](https://www.countrycalling.codes/api/calling-codes?q=united%20kingdom) - [Reviewed example data](https://www.countrycalling.codes/api/calling-codes?code=GB&include=examples) - [Direct lookup API](https://www.countrycalling.codes/api/calling-codes/gb) - [Dial-code lookup](https://www.countrycalling.codes/api/calling-codes?dialCode=44) - [Region filter](https://www.countrycalling.codes/api/calling-codes?region=Europe) - [Sitemap](https://www.countrycalling.codes/sitemap.xml) - [Robots](https://www.countrycalling.codes/robots.txt) ## Formatting Facts - An international E.164 number combines a country calling code with the destination national significant number and contains at most 15 digits. - The plus sign signifies the international prefix in written notation. It is not itself a country code or an E.164 digit. - An exit prefix such as 00, 010, 011, or 0011 belongs to the origin dial string, not the stored destination number. - Country-pair walkthroughs show both the portable + format and the digits-only dial string for a specific origin. Carrier-selection codes remain origin routing instructions rather than part of the saved destination number. - A leading zero is country-specific. It is removed in many plans but retained on Italian geographic numbers. - Spaces and punctuation are display characters. Store extensions separately. - Use X placeholders in published patterns unless a reserved example number is explicitly identified. - Forms and CRMs should preserve original input, use explicit country context, normalize safely, store +digits only after parsing, and keep extensions separate. - A top-level code can be shared: later digits distinguish destinations inside +1, +7, +39, +61, +262 and +599 in this directory. - National toll-free numbers are not necessarily reachable abroad. A UIFN uses +800 plus eight digits, subject to subscriber and originating-network support. - Failed calls can originate in formatting, account permissions, carrier routes, destination filtering, congestion, or VoIP signalling and media—not one layer. ## Reviewed Country-Pair Pages - [Call the United Kingdom from the United States](https://www.countrycalling.codes/call/united-kingdom-from-united-states) - [Call the United States from the United Kingdom](https://www.countrycalling.codes/call/united-states-from-united-kingdom) - [Call Italy from Germany](https://www.countrycalling.codes/call/italy-from-germany) - [Call Singapore from Australia](https://www.countrycalling.codes/call/singapore-from-australia) - [Call Japan from Singapore](https://www.countrycalling.codes/call/japan-from-singapore) - [Call the United States from Brazil](https://www.countrycalling.codes/call/united-states-from-brazil) - [Call India from the United States](https://www.countrycalling.codes/call/india-from-united-states) - [Call Australia from the United States](https://www.countrycalling.codes/call/australia-from-united-states) - [Call Germany from the United States](https://www.countrycalling.codes/call/germany-from-united-states) - [Call India from the United Kingdom](https://www.countrycalling.codes/call/india-from-united-kingdom) - [Call the United Kingdom from Australia](https://www.countrycalling.codes/call/united-kingdom-from-australia) - [Call the United States from Japan](https://www.countrycalling.codes/call/united-states-from-japan) ## API Summary GET /api/calling-codes Query parameters: - q: free text search across country name, official name, ISO codes, dial code, capital, and area codes. - code: ISO 3166-1 alpha-2 or alpha-3 country code, such as GB or GBR. - dialCode: country calling code with or without "+", such as +44 or 44. This field is not a complete phone number. - region: Africa, Americas, Asia, Europe, or Oceania. - limit: maximum number of returned countries. - include: set to examples to add reviewed dialingGuide content, source URLs, safe mobile/landline patterns, exceptions, and lastVerified metadata. Omitted by default to keep lookup payloads compact. GET /api/calling-codes/{lookup} Lookup may be an ISO alpha-2 code, ISO alpha-3 code, country slug, country name, or dial code. Dial codes can be passed as 44 or encoded as %2B44. Append ?include=examples for reviewed guidance when available. GET /api/calling-codes/openapi.json OpenAPI 3.1 schema for generating a read-only LLM tool. GET /api/calling-codes/status Uncached live status, API version, dataset counts, and canonical endpoint links. The REST endpoints support cross-origin GET requests and return structured HTTP 400 errors for invalid query parameters. POST /api/phone/format Accepts JSON with a required phoneNumber and optional two-letter countryCode. It applies the same reviewed formatter as the browser tool, processes the value ephemerally, never caches the response, and never represents the result as a carrier, HLR/HSS, MNP, allocation, reachability, ownership, or consent check. GET /skill.json Machine-readable skill manifest with guide, API, MCP, and OpenAPI entry points. POST /api/mcp Streamable HTTP MCP server exposing lookup_country_calling_code and format_international_phone_number. Set includeExamples=true to request the reviewed dialing guide. Phone-format input is processed ephemerally. A normal browser GET returns discovery and client-configuration JSON; MCP clients negotiate the Streamable HTTP transport at the same URL. The Registry-format manifest is at /server.json. ## Enhanced workflows (API 1.4.0) GET /api/capabilities lists operation coverage, evidence and limits. The MCP server also offers analyze_phone_number, get_dialing_instructions, normalize_phone_numbers, compare_phone_numbers, resolve_phone_region, get_phone_input_rules, diagnose_dialing_problem, find_calling_windows, and get_phone_capabilities. See /developers#enhanced-api and /api/calling-codes/openapi.json for exact contracts. Number analysis uses versioned numbering metadata, separately labeled from the 13 editorially reviewed country guides. Supply numberCountryCode for national input and originCountryCode for exit prefixes. Batches accept up to 100 uniquely identified items with per-record errors. POST bodies are limited to 64 KiB. Calling windows use explicit IANA time zones, local schedules and a date range of at most 31 days. MCP clients and third-party gateways may retain their own history even when our number processing is ephemeral. No operation verifies live subscribers. ## Validation Boundaries Formatting/plausibility checks are not live verification. Carrier, MNP, or HLR/HSS results are provider-reported and time-sensitive. They do not prove identity, ownership, current ability to answer, or consent. When control matters, use a short-lived challenge and retain the result only for the defined purpose. ## Public Pages - [Homepage](https://www.countrycalling.codes/) - [Directory](https://www.countrycalling.codes/directory) - [Guides](https://www.countrycalling.codes/guides) - [International dialing format](https://www.countrycalling.codes/guides/international-dialing-format) - [Phone number format for forms, CRM and SMS](https://www.countrycalling.codes/guides/phone-number-format-for-forms-crm-sms) - [Shared country codes](https://www.countrycalling.codes/guides/shared-country-codes) - [International toll-free calling](https://www.countrycalling.codes/guides/international-toll-free-calling) - [International call troubleshooting](https://www.countrycalling.codes/guides/international-call-troubleshooting) - [Avoid roaming charges](https://www.countrycalling.codes/guides/avoid-roaming-charges) - [Travel eSIM vs roaming vs local SIM](https://www.countrycalling.codes/guides/travel-esim-vs-roaming-vs-local-sim) - [Country dialing walkthroughs](https://www.countrycalling.codes/guides/country-dialing-walkthroughs) - [Phone number validation](https://www.countrycalling.codes/guides/phone-number-validation) - [Common formatting errors](https://www.countrycalling.codes/guides/common-phone-number-formatting-errors) - [Satellite and non-geographic codes](https://www.countrycalling.codes/guides/satellite-non-geographic-calling-codes) - [Call routing and number portability](https://www.countrycalling.codes/guides/call-routing-number-portability) - [Format checker](https://www.countrycalling.codes/tools/format-checker) - [Methodology](https://www.countrycalling.codes/methodology) - [Developer documentation](https://www.countrycalling.codes/developers) - Country detail template: `/country/{slug}` - [Privacy](https://www.countrycalling.codes/privacy) - [Contact](https://www.countrycalling.codes/contact)