### Answer Retell AI automatically provides the caller's phone number through the

{{user_number}}

system variable [(1) ]() . This variable is available by default for phone calls and requires no configuration . To use it in your agent, reference

{{user_number}}

in your prompts . For example, you can include it in your global prompt or first message like:

"I see you're calling from {{user_number}}"

For phone calls,

{{user_number}}

represents the user's phone number - specifically the

from_number

for inbound calls or the

to_number

for outbound calls . If you need to pass the caller's phone number to external systems or webhooks, you can also access it through the inbound call webhook, which provides both

from_number

and

to_number

in the payload [(2) ]() . **Testing tip**: To verify the variable is working, you can temporarily set your first message to explicitly state the number, like "Is this your phone number: {{user_number}}?" . This helps confirm the variable is populating correctly before using it in your production prompts.

​ To learn more, see the sources I considered: [[1] Dynamic Variables](https://docs.retellai.com/build/dynamic-variables) [[2] Caller ID ({{user_number}}) will not register in AI Agent](https://discord.com/channels/1186424376300679209/1387609283322974299) ​

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