Unaric Voice 

Dialing Rule

Amazon Connect requires to dial a phone number E.164 format. E.164 numbers are formatted [+] [country code] [subscriber number including area code] and can have a maximum of fifteen digits.

You need to enable this option in the dialing rules.

Select in the main Main Call Center Setup the dialing rule : Amazon Connect - Dialing Option - International Setup or Amazon Connect - Dialing Option - US Setup