# PrefixBook > PrefixBook is an independent reference site about phone number prefixes: the +1 country code, area codes, 011 versus the plus sign, when to dial 1, calls to Canada and the Caribbean, and 900 pay-per-call numbers. Its small reader shows only what the digits say (region, time zone, toll-free or premium flags) and never identifies an owner, carrier or line type. It is not affiliated with any carrier, agency or people-search company and does not sell data. Editorial site about identifying unknown phone callers and understanding US/NANP area codes. It does not sell personal data and does not claim to identify the owner of a number. Written by Marit Holloway. Contact: hello@prefixbookpro.com. ## Guides - [Why numbers start with +1, and how country calling codes work](https://prefixbookpro.com/why-numbers-start-with-plus-one): The +1 on a US number is a shared country calling code for the whole North American plan. Quick answers on how codes work and which places share it. - [Dialing internationally from the US: a glossary from 011 to the plus sign](https://prefixbookpro.com/dial-internationally-011-vs-plus): A plain-word glossary of international dialing from the US: exit code, country code, trunk prefix, 011, the plus sign and why a copied number fails. - [When do you dial 1 before the area code?](https://prefixbookpro.com/when-to-dial-1-before-area-code): An essay on the 1 before an area code: what it was for, how overlays and 988 changed the rules, and how mobiles, landlines and office phones differ. - [How to call Canada and the Caribbean from the US without a surprise bill](https://prefixbookpro.com/calling-canada-and-the-caribbean-from-the-us): Calls to Canada and Caribbean islands dial like domestic calls but may bill as international. Steps to check a code, place the call and handle one-ring scams. - [900 numbers and pay-per-call prefixes: nine myths, checked](https://prefixbookpro.com/900-numbers-and-pay-per-call-prefixes): Nine common beliefs about 900 numbers and toll-free codes, each checked: who pays, why a 900 number calls you, what blocking does and what disputes can win. - [011, 00 and the plus sign: a checklist for how other countries dial out](https://prefixbookpro.com/how-other-countries-dial-out-00-011-plus): A checklist for dialing out and sharing your number: 011 in the US, 00 in much of Europe, why the plus sign works everywhere and what to check before you travel. - [Country calling codes cheat sheet: reading the first digits of a number](https://prefixbookpro.com/country-calling-codes-cheat-sheet): A cheat sheet for the first digits of a number: world zones 1 to 9, 26 common country codes, look-alikes such as 212 and +212, and dialing recipes. - [Dialing the US from abroad: messages and formats you can copy](https://prefixbookpro.com/dialing-the-us-from-abroad): Copy-ready messages for calling a US number from abroad: the plus, 1 and ten digits format, a hotel desk line, toll-free workarounds and time zones. - [Calling cards and international calling apps: how the number shows up, in four sample calls](https://prefixbookpro.com/calling-cards-and-calling-apps-caller-id): Four invented sample calls show what caller ID can display when a call starts on a prepaid card, an app or a hotel phone, with notes on each line. - [How to save contacts in international format: one invented week, and the fix](https://prefixbookpro.com/save-contacts-in-international-format): An invented but typical story shows why contacts saved without a country code, or with a stray 1 or zero, fail abroad, and how to repair them on iPhone and Android. ## Tools and data - [Phone prefix lookup](https://prefixbookpro.com/dial-prefix-lookup): Type a US or Canadian number to see its area code region, country or service type and time zone. It does not reveal the owner or carrier. ## About - [Phone prefixes, country codes and area codes, explained](https://prefixbookpro.com/): Plain answers on +1, area codes, 011 versus the plus sign, dialing 1, Canada and Caribbean calls, and 900 numbers, plus a reader for any prefix. - [About PrefixBook](https://prefixbookpro.com/about-prefixbook): Who runs PrefixBook, what the reader does and does not do, how facts are checked and dated, and how to send us a correction. - [Marit Holloway](https://prefixbookpro.com/marit-holloway-editor): Meet Marit Holloway, who writes and edits PrefixBook, checks each claim against its source and dates every page she rereads. - [Contact PrefixBook](https://prefixbookpro.com/contact-prefixbook): Send a correction, a dialing question or a privacy request to PrefixBook. What to include and what we cannot help with. - [Privacy policy](https://prefixbookpro.com/privacy-policy): What PrefixBook collects: no accounts or cookies, server logs for about a week, contact messages kept up to a year, and your CCPA rights. - [Terms of use](https://prefixbookpro.com/terms-of-use): The rules for using PrefixBook: informational purposes only, no harassment or tracking, no warranty, limits of liability and governing law. - [Disclaimer](https://prefixbookpro.com/disclaimer): PrefixBook is independent and informational. What tool results mean, why we give no guarantees, and our Do Not Sell or Share statement.