"Even if the invite is being sent via sms (which should just require the phone
number), the list will require an email address (even if it is a dummy one)
along with the actual phone number.
If the phone number is present and the email address field is empty, the
sms will not be sent/received at all.
You can refer to the screenshot below for an example on how to upload the
list while sending invites via sms:
https://app.screencast.com/nD3ObLS3yOmKA"