var headerNames = ["Authorization"];
var headerValues = ["Bearer " + accessToken];
var smsEndpoint = "https://mcvwf-nkxrzjq7703k4qnp23fgt1.rest.marketingcloudapis.com/";  //provide rest endpoint
var smsPayload = '{';
    smsPayload += '"mobileNumbers": [';
    smsPayload += '"34xxxxxxxxx"';  //pass phone number country code + pnonenumber
    smsPayload += '],';
    smsPayload += '"Subscribe": true,';
    smsPayload += '"Resubscribe": true,';
    smsPayload += '"keyword": "TriggeredSMS"';  //provide KEYWORD
smsPayload += '};';

var smsAPIKey = "NzQ4Ojc4OjA";

var smsUrl = smsEndpoint + "/sms/v1/messageContact/" + smsAPIKey + "/send";  //provide message API key

try {

var sendSMS = HTTP.Post(smsUrl, contentType, smsPayload, headerNames, headerValues);

} catch (error) {
    Write('<h1>SMS call</h1></br>');
    Write('smsUrl: ' + smsUrl + '</br>');
    Write('smsPayload: ' + smsPayload + '</br>');
    Write(Stringify(error));
    Write('</br>');
}