I know:(, sorry. Reason is I'm using Twilio for the text messages and non-US numbers are really expensive. Since I'm not trying to monetize it I want to make sure that I am able to fund it out of my pocket.
I don't know about non-US numbers, but you can send text messages via email for free. You can usually do that by sending the email to the user's number at their provider. There are sites on the internet that will give you the user's provider from the phone number.
For example, a user who has AT&T can receive a text by emailing it to <phonenumber>@txt.att.net.
