TCR Text Campaign Error 804
Unable to verify, need a website/working website or complete call to action (CTA) information if opt-in occurs outside the website.
You did not supply a website URL, or the website URL you supplied is not working. If you do not have a website and collect permission to send texts to your customers and prospects differently, the carriers will need to see how opt-in is performed. Note opt-in must be written and recorded in some fashion.
Remedy
A working website and opt-in page are the easiest way to demonstrate to the carrier that you have an opt-in mechanism in place.
Your website should also contain a compliant privacy policy that states that mobile numbers collected for opt-in are not shared or sold for marketing purposes.