# Working with Phone Numbers

When sending phone numbers into CrowdPower, it is best to use the E.164 standard. E.164 is the international telephone numbering plan that ensures each device on the Public Switched Telephone Network (PSTN) has a globally unique number. This number makes sure phone calls and text messages can be correctly routed to phones in different countries.

E.164 numbers are formatted: **\[+] \[country code] \[area code and number]** and can have a maximum of 15 digits.

An example of a US number in E.164 format is: **+15165555555**