### Answer Yes, you can use the

user_first_name

variable in your greeting by returning it from your inbound webhook and then referencing it with the

{{user_first_name}}

syntax. [(1) ]() In your inbound webhook response, return the dynamic variable like this:

json
{
  "call_inbound": {
    "dynamic_variables": {
      "user_first_name": "John"
    }
  }
}

[(2) ]() Then in your agent's begin message (greeting) , use the placeholder:

"Hello {{user_first_name}}, thanks for calling!"

[(1) ]() Dynamic variables can be used in prompts and the begin message, so once you return

user_first_name

from your inbound webhook, the agent will substitute it into the greeting. If the variable isn't provided or is empty, it will remain as

{{user_first_name}}

in the output, so you may want to add defensive prompting to handle cases where the user isn't found.

​ To learn more, see the sources I considered: [[1] Dynamic Variables](https://docs.retellai.com/build/dynamic-variables) [[2] Dynamic Variables](https://discord.com/channels/1186424376300679209/1356680357084135558) ​

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

### Answer Yes, that approach is correct. You can add conditional logic in your prompt to handle unset variables. [(1) ]() The documentation specifically recommends this pattern for handling missing variables:

If {{user_name}} appears with curly braces, use a generic greeting.
Otherwise, greet the customer by name.

Your prompt structure follows this pattern well. When

{{user_first_name}}

has no assigned value, it remains in its raw form with the curly braces intact, so your conditional logic can detect that and fall back to the generic greeting. You can also use the

exists

check in Conversation Flow equations if you're using that builder:

Equation: {{user_name}} exists
Result: True if variable is set

​ To learn more, see the sources I considered: [[1] Dynamic Variables](https://docs.retellai.com/build/dynamic-variables) ​

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