There are two reasons why your auto-responses would fail. We'll start off with the most popular of the two.
vCard Image File Size Exceeds 150KB
When editing your vCard please be sure to upload an image with a file size that is under 150KB!!! - Are you unsure what a vCard is? Check out this article here.
DOWNSIZE IMAGE FOR YOUR vCard here.
Carriers, T-Mobile, AT&T, Verizon & Sprint to name a few, have limits on file sizes accepted to them from SuperPhone numbers. Anything over the allocated amount will result in your message returning a failed status in SuperPhone. That error looks something like this...
If you are running into this issue, edit the image that you have imported. You can configure or edit your vCard at the bottom of your profile page here: https://app.superphone.io/profiles
Here's how to check the file size of your image..
International Phone Numbers
Having an international is great but has it's disadvantages. International numbers do not support MMS messages. This means you are not allowed to send out photos, GIF's, videos or vCards with international numbers.