### Answer For inbound calls, the recommended approach is to capture the caller's phone number at call start using the inbound webhook, not mid-conversation. When an inbound call begins, Retell sends a POST request to your configured inbound webhook URL, which includes the

from_number

. You can then return this as a dynamic variable that your agent can access throughout the call. [(1) ]() You can set the inbound webhook URL within the Dashboard or via API. Whatever you return in the webhook response becomes available as dynamic variables—for example, if you return

{"phone_number": "780-555-1212"}

, you can then reference

{{phone_number}}

in your prompt. There are also system default dynamic variables available for phone calls, including: - `{{user_number}}`: the user's phone number (for inbound calls, this is the

from_number

) - `{{agent_number}}`: the agent's phone number (for inbound calls, this is the

to_number

) [(2) ]() So while you can't retrieve the

from_number

mid-conversation via a separate API call, you can access it throughout the call if you either: 1. Capture it via the inbound webhook at call start and pass it as a dynamic variable 2. Use the

{{user_number}}

system dynamic variable Check out these potentially useful sources for more details: - [Dynamic Variables for Inbound Calls]()

​ To learn more, see the sources I considered: [[1] Discord message from @danishkhan18 on 2025-01-27](https://discord.com/channels/1186424376300679209/1186462578310910112/1333229197002543127) [[2] Platform Changelogs | Retell AI](https://www.retellai.com/changelog) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.