Why Your AI Agent's Phone Number Gets Blocked (And How to Fix It)

You built an AI agent that onboards to a new service, creates an account, fills in a form, and gets all the way to SMS verification - then hits a wall. "This number cannot be used for verification." Or worse: the code is never sent and no error appears at all. Your agent just sits there waiting. This is the VoIP blocking problem. It affects every AI agent that needs a real identity, and it's getting worse as fraud rates on virtual numbers rise. This guide explains exactly what's happening, why every major service blocks VoIP numbers, and what the working alternatives are.