Hi ebclc,
You are probably right, Qualtrics is really strict on requiring country code in front of a mobile number.
If you're wanting to handle this on Qualtrics's side, you could add a Code task to grab the phone number from the JSON, add a 1 in front of it and then send it down to the rest of the workflow.
Good luck!

Thanks bgooldfed! Yes this looks like what I need to do. I had a go but I'm new to this and think there's an error in my code below - any ideas? Thanks for any help you can offer.
---
function codeTask() {

let us_country_code = "1-";
var phone = us_country_code.concat("", phone)

             return {
                          result: phone
             }
}

https://community.qualtrics.com/XMcommunity/discussion/comment/48907#Comment_48907It looks like you're not bringing in the phone variable correctly. It's in a JSON from the API call made by the CMS right?
You can pipe in data from webservices like so:
Which will display everything fetched from the JSON (this is a random example from a workflow I had set up in the past):
Store that in a variable and then you should be able to contact it with the country code. The rest of your code looks fine.
PS: I don't think you need to append the "-" to the number for Qualtrics to send mobile texts. I've always managed to just use the full number eg: 1555555555

Thanks very much bgooldfed, that worked! For anyone who needs to see the solution, here's what worked for me.
I added a CodeTask step after my JSON event. This takes the original "phone" value from the API call and formats it to include a "1-" in front.
function codeTask() {
let text1 = "1-";
let text2 = "~{aed://phone}";
let text3 = text1.concat("",text2);
return {
formatted_phone: text3
}
}
Then, in my next workflow step (XM Directory), I have the value for "Phone" piped in from the preceding task result, i.e. "formatted_phone".

https://community.qualtrics.com/XMcommunity/discussion/comment/49032#Comment_49032Well done, glad it is working If my comment solved the issue, please accept it as the answer.
Cheers!

Thanks bgooldfed. I think I've accepted the answer now!