Note: This article is in conjunction with the following articles: Understanding PBX for Voice AI, Overflow and After-Hours Voice AI Receptionist and Understanding Call Forwarding to Voice AI Agent. Make sure to read these articles before you purchase a phone number or read the current article.
Regular phone numbers vs Programmable phone numbers. Understand the difference.
Voice AI platforms like ‘Retell AI’ cannot connect a ‘regular’ phone number (like a personal mobile or landline) directly to its AI agents.
You would need to first purchase and use a programmable phone number. Then set up call forwarding from your regular number to the programmable number.
Programmable phone numbers are virtual phone numbers that you can fully control with software, usually through an API.
Unlike a regular phone number that’s tied to a SIM card, handset, or fixed line, a programmable number lives in the cloud and can be configured in real time to send/receive calls and messages, trigger code, and integrate with applications.
With programmable phone numbers, you can:
- Route calls using APIs or custom call-handling logic.
- Trigger webhooks for real-time AI interactions.
- Use SIP trunking to connect with external systems.
Standard phone numbers from traditional carriers (Vodafone, Verizon, Airtel, etc.) are tied directly to their network and devices.
They don’t allow you to insert a webhook, SIP endpoint, or third-party platform between the carrier and your phone, which means they can’t provide these advanced capabilities.
For full AI agent automation, you must purchase and use a virtual/programmable number.