Hi @cmieloch
Welcome to the Auth0 Community!
I am sorry regarding the late reply to your inquiry.
The gateway_url that you need to use a parameter as per our documentation when setting up the SMS gateway should be the URL provided by Azure Communication Services.
The URL should look something like this:
“gateway_url”: “https://{YOUR_CUSTOM_DOMAIN_URL}/API/V1//SMS/{{ phone_number }}/AUTOGEN/OTP”
The gateway URL depends on what your phone providers uses, you should be able to consult their documentation on the matter.
Hope this helps, if you have any additional questions, feel free to leave a reply on the post.
Kind Regards,
Nik