Why do some phone numbers have an address requirement?

Due to local regulations, some phone numbers require the user to be located in a particular region or to list their information in order to purchase and own the number. The address you provide can be a business or personal address that you, your company, or your customer who will be using the phone number(s) has.

There are three types of address requirements:
Any: You must provide an address anywhere in the world.
Local: You must be located in and provide an address within the phone number’s country.
Foreign: You must be located outside and provide an address outside the phone number’s country.

When purchasing phone numbers which require addresses, Twilio will require you to file a qualifying address with us before you are able to purchase the phone number. After creating that address once, it can be used as many times as you’d like for the account on which the address was created. We will use this address in the event that we are contacted by authorities in that country. If you own several phone numbers for different customers in a particular country, we encourage you to add multiple addresses – one per customer.

A detailed list of countries that have address requirements can be found here, although the best way to filter is using the list filters on Twilio’s AvailablePhoneNumbers resource or the Advanced search features within the API.