Fix: Google 'This number cannot be used' for AI Agent Verification

Building AI agents that need Google accounts? You've hit "This number cannot be used" — Google's most aggressive VoIP block. Here's the technical breakdown and the fix. How Google Detects VoIP Numbers Google runs the most sophisticated phone verification in the industry, layering multiple checks: 1. Real-time HLR Queries Google queries the Home Location Register of the number's carrier. Real mobile numbers return active network registration. VoIP numbers either fail HLR entirely or return internet-based routing. 2. LERG Database Lookup The Local Exchange Routing Guide maps every North American number to its carrier. Google cross-references this — if your number belongs to Twilio, Bandwidth, or any VoIP provider, it's rejected before the SMS is even queued. 3. Behavioral Analysis Google tracks creation patterns: how many accounts were created from this number, geographic consistency between the number's area code and the IP address, and timing patterns that suggest automation. Why Every