Phone Number Formatting

Phone numbers can be written in different ways. For example +1 (555) 857-6309 is the same phone number as +1-555-857-6309. To avoid issues that might arise when dealing with different phone number formats, we convert all phone numbers to a common format.

For storing and displaying phone numbers, we always use the E.164 standard format (without the ‘+’ international call prefix). This format makes the phone numbers easily transferrable and comparable.

When sending a message, Amio API accepts all phone number formats. However, the phone number will be converted to E.164 format internally. All Amio webhooks and responses will always contain the E.164 formatted phone number.


Every Amio contact has a unique ID that can be used to track the contact instead of its phone number.

If you need to convert a phone number to E.164 format, remove every character that is not a digit.

  • Example: +1 (555) 857-6309 → 15558576309