### Answer You can use dynamic variables in your prompts using the

{{variable_name}}

syntax. [(1) ]() How to pass dynamic variables: For Outbound Calls: Use the

retell_llm_dynamic_variables

field when calling the Create Phone Call API:

json
{
  "user_name": "John Smith",
  "product_name": "Premium Plan",
  "account_status": "active"
}

For Inbound Calls: Supply dynamic variables via the Inbound Call Webhook. Example prompt usage:

"Hello {{user_name}}, I understand you're interested in {{product_name}}. How can I help you today?"

Where dynamic variables work: - Prompts - Begin message - Tool configurations (custom function URLs, tool descriptions, property descriptions) - Voicemail prompts and messages - Transfer call phone numbers - Warm transfer instructions - Webhook URL You can also set default values for dynamic variables at the agent level in the dashboard, which serve as fallbacks when variables aren't included in the call request. Note: All values in

retell_llm_dynamic_variables

must be strings—numbers, booleans, or other data types are not supported.

​ 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.

@AI Evy If my custom variable fullname "Hi {{fullname}}, how are you today?" is this correct?

### Answer Yes, that syntax is correct. [(1) ]() Using

"Hi {{fullname}}, how are you today?"

follows the proper

{{variable_name}}

format for dynamic variables in prompts. Just make sure you pass the

fullname

value when initiating the call. For outbound calls, include it in the

retell_llm_dynamic_variables

field:

json
{
  "fullname": "John Smith"
}

Note: If

fullname

is not provided, the prompt will display the raw placeholder:

"Hi {{fullname}}, how are you today?"

​ 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.

### Answer Here's an example prompt using dynamic variables:

"Hello {{user_name}}, I understand you're interested in {{product_name}}. How can I help you today?"

[(1) ]() Common use cases from the documentation: - **Personalized greetings**:

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

- **Context-aware responses**:

"I see you're calling about order {{order_id}}"

- **Time-sensitive information**: Reference

{{appointment_date}}

or

{{deadline}}

When passing these variables for an outbound call:

json
{
  "user_name": "John Smith",
  "product_name": "Premium Plan",
  "account_status": "active"
}

You can also use system variables that Retell provides automatically: -

{{current_time}}

– Current time in America/Los_Angeles -

{{user_number}}

– User's phone number -

{{direction}}

– Call direction (inbound or outbound) Tip: Ensure there are no spaces inside the curly braces. Use

{{fullname}}

not

{{ fullname }}

. [(2) ]()

​ To learn more, see the sources I considered: [[1] Dynamic Variables](https://docs.retellai.com/build/dynamic-variables) [[2] Issue with Dynamic Variables.](https://discord.com/channels/1186424376300679209/1336469878068219904) ​

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

### Answer Yes, Retell offers embeddable website widgets for both chat and voice interactions. [(1) ]() Chat Widget – Text-based conversations using a chat agent. Callback Widget – Phone-based conversations using a voice agent (collects user info and initiates a phone call) . How to embed the Chat Widget: Add this script to your HTML

<head>

tag:

html
<script
  id="retell-widget"
  src="<https://dashboard.retellai.com/retell-widget.js%22>
  type="module"
  data-public-key="YOUR_RETELL_PUBLIC_KEY"
  data-agent-id="YOUR_CHAT_AGENT_ID"
  data-agent-version="YOUR_AGENT_VERSION"
  data-title="YOUR_CUSTOM_TITLE"
></script>

How to embed the Callback Widget (for voice/phone) :

html
<script
  id="retell-widget"
  src="<https://dashboard.retellai.com/retell-widget.js%22>
  type="module"
  data-public-key="YOUR_RETELL_PUBLIC_KEY"
  data-agent-id="YOUR_VOICE_AGENT_ID"
  data-widget="callback"
  data-phone-number="YOUR_RETELL_PHONE_NUMBER"
  data-title="Request a Call"
></script>

Prerequisites: - Create a [Public Key]() in your Retell dashboard - For chat: Create a chat agent - For callback: Create a voice agent and have a Retell phone number Note: Currently, using both widgets on the same webpage has a known limitation—they share the same

id="retell-widget"

, so only one displays at a time. This is on the roadmap to be resolved. [(2) ]()

​ To learn more, see the sources I considered: [[1] Retell Website Widget](https://docs.retellai.com/deploy/chat-widget) [[2] MULTIPLE WIDGETS (AI VOICE AGENT AND CHAT AGENT) ON THE SAME WEBPAGE?](https://discord.com/channels/1186424376300679209/1446532249041506445) ​

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

### Answer Yes, Retell AI agents can press digits (DTMF tones) during calls to navigate IVR systems. [(1) ]() How it works: The Press Digit Tool gives your agent the ability to send DTMF input when encountering IVR menus. Setup steps: 1. Add a Press Digit Tool to your agent – this enables the digit-pressing capability 2. Add prompts to guide the agent on when and what digits to press. Example prompts:

You are going to call to a business and they may have IVR setup.
Listen carefully to their setup and press the right digit to navigate 
the IVR to reach the support department.

Or if you know the digit beforehand:

Press digit 1 to reach the support department.

Important notes: - This functionality only works with Call API v2 - Some IVRs accept audio input (just prompt your agent to speak) , while others require DTMF input (use the Press Digit Tool) - You can also capture DTMF input from users via the Listen to User Keypad Input feature [(2) ]()

​ To learn more, see the sources I considered: [[1] Press digit (IVR navigation)](https://docs.retellai.com/build/single-multi-prompt/press-digit) [[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.

### Answer You have several options to test the Press Digit (IVR navigation) functionality: Option 1: Make a Test Outbound Call [(1) ]() Use Web Call or Phone Call Testing for real-world testing with actual voice interactions. You can test outbound calls directly from the dashboard by clicking "Make an outbound call" and entering the phone number with country code. [(2) ]() Option 2: LLM Simulation Testing [(3) ]() Click "AI Simulated Chat" to create a new test case and define a user prompt simulating an IVR scenario. Example format:

## Identity
Your name is Mike.

## Goal
Your primary objective is to navigate the IVR menu to reach the support department.

## Personality
You are a patient customer.

Option 3: LLM Playground [(1) ]() Use the interactive text-based testing for rapid iteration and debugging. This allows real-time conversation testing and function call visualization. Recommended workflow: - Phase 1 (Development) : Use LLM Playground to iterate on prompts and debug function calling logic - Phase 2 (QA) : Use LLM Simulation Testing to create comprehensive test scenarios - Phase 3 (Production Validation) : Use actual phone calls to verify DTMF features work in real telephony conditions Note: For testing Press Digit functionality specifically, actual phone call testing is recommended since it validates real DTMF tone transmission.

​ To learn more, see the sources I considered: [[1] Testing Overview](https://docs.retellai.com/test/test-overview) [[2] How can I create an outbound call](https://retell.discourse.group/t/how-can-i-create-an-outbound-call/132) [[3] Automatically test your agent](https://docs.retellai.com/test/llm-simulation-testing) ​

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

### Answer For testing IVR navigation with Press Digit functionality, you need to make real phone calls to fully validate DTMF tone transmission. [(1) ]() Why real calls are needed for IVR testing: The testing comparison shows that LLM Playground and LLM Simulation testing do not support testing features like background noise, interruptions, or telephony-specific features like DTMF. | Feature | LLM Playground | LLM Simulation | Web/Phone Call | |---------|----------------|----------------|----------------| - **LLM Playground**: ❌ Does not test DTMF/telephony features - **LLM Simulation**: ❌ Does not test DTMF/telephony features - **Web/Phone Call Testing**: ✅ Validates DTMF and telephony features Recommended approach: - **Phase 1-2 (Development/QA) **: Use LLM Playground or Simulation to test your agent's logic and prompts for when to press digits - **Phase 3 (Production Validation) **: Use actual phone calls to verify the DTMF tones work correctly with real IVR systems Web/Phone Call Testing is described as "Best For: Final validation, voice quality testing, production readiness checks" and specifically lists "Verify DTMF and telephony features" as a key feature.

​ To learn more, see the sources I considered: [[1] Testing Overview](https://docs.retellai.com/test/test-overview) ​

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

### Answer Retell AI uses a pay-as-you-go billing model—you don't pre-load credits. [(1) ]() How it works: Services are charged on a monthly basis. You provide a valid credit card, and Retell automatically charges your card at the end of the month for your usage. To set up or update your payment method: 1. Navigate to the Billing tab in your dashboard [(2) ]() 2. Click "Change payment methods" 3. In the Stripe portal, click "Add payment method" and enter your payment details Key points: - There's no "add credit" option—you pay based on actual usage at the end of each billing period [(3) ]() - If you want to pre-fund your account, you can credit an amount first, and it will be deducted according to usage - Your payment information is securely handled by Stripe [(2) ]() If you're seeing a "payment overdue" error, go to the Billing tab and pay any past invoices first. [(4) ]()

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

​ To learn more, see the sources I considered: [[1] Retell | Terms Of Service](https://www.retellai.com/legal/terms-of-service) [[2] Add payment methods](https://docs.retellai.com/accounts/add-payment) [[3] Workspaces billing](https://discord.com/channels/1186424376300679209/1384656040758481017) [[4] Unable to Make Calls – Account Shows Zero Balance After Payment](https://discord.com/channels/1186424376300679209/1394737867695325214) ​

### Answer Post-call analysis data is only included in the

call_analyzed

webhook event—not in

call_started

or

call_ended

. [(1) ]() Key things to check: 1. Filter for the correct event type – Retell sends three webhooks per call:

call_started

,

call_ended

, and

call_analyzed

. The post-call analysis fields (

call_analysis

object) are only populated in the

call_analyzed

event. [(2) ]() , [(1) ]() 2. Webhook payload structure – The

call_analyzed

webhook includes the call object with the

call_analysis

field:

json
{
  "event": "call_analyzed",
  "call": {
    "call_id": "123",
    "call_analysis": {
      "call_summary": "...",
      "custom_analysis_data": {}
    }
  }
}

[(2) ]() , [(1) ]() 3. Calls must have a conversation – Post-call analysis fields will not be populated for calls that were not connected or where no conversation took place. [(2) ]() 4. Check if analysis appears in dashboard – If you see the analysis results in your dashboard's call history but not in the webhook, confirm you're listening for the

call_analyzed

event specifically. , [(3) ]() Troubleshooting tip: When testing, make a call, then check your webhook logs for three separate events. The post-call analysis data will only be in the third one (

call_analyzed

) . [(4) ]() , [(5) ]()

​ To learn more, see the sources I considered: [[1] Webhook Overview](https://docs.retellai.com/features/webhook-overview) [[2] Consume the analysis data](https://docs.retellai.com/features/post-call-analysis-consumption) [[3] postPost-call analysis: Data is gathered but not sent via webhook..why?](https://discord.com/channels/1186424376300679209/1399744779998461952) [[4] Discord message from @keshav3 on 2025-01-30](https://discord.com/channels/1186424376300679209/1186462578310910112/1334444968156332126) [[5] Discord message from @heavenly.rain on 2025-08-25](https://discord.com/channels/1186424376300679209/1186462578310910112/1409343556870471732) ​

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

### Answer To get custom post-call data extraction (not just the default analysis) , you need to configure

post_call_analysis_data

on your agent. [(1) ]() Step 1: Define custom extraction fields on your agent Use the Update Voice Agent API to add your custom analysis categories:

json
"post_call_analysis_data": [
  {
    "type": "string",
    "name": "customer_name",
    "description": "The name of the customer.",
    "examples": [
      "John Doe",
      "Jane Smith"
    ]
  }
]

Available data types you can extract: [(2) ]() - Boolean (True/False) – e.g., whether customer is a first-time caller - Text (String) – e.g., call summaries, action items - Number – e.g., transaction amounts, satisfaction scores - Selector (Enum) – categorization from a fixed list Step 2: Access your custom data via webhook Your custom extraction data appears in the

call_analyzed

webhook under `custom_analysis_data`: [(3) ]() , [(4) ]()

json
{
  "event_type": "call_analyzed",
  "call": {
    "call_analysis": {
      "call_summary": "...",
      "custom_analysis_data": {}
    }
  }
}

​ To learn more, see the sources I considered: [[1] Update Voice Agent](https://docs.retellai.com/api-references/update-agent) [[2] Post Call Analysis Overview](https://docs.retellai.com/features/post-call-analysis-overview) [[3] Consume the analysis data](https://docs.retellai.com/features/post-call-analysis-consumption) [[4] Get Call](https://docs.retellai.com/api-references/get-call) ​

[(3) ]() , [(4) ]() Important notes: - Custom post-call analysis fields will not be populated for calls that were not connected or where no conversation took place [(3) ]() , [(2) ]() - You can also set

post_call_analysis_model

to choose which model performs the analysis (default is

gpt-4.1-mini

) [(1) ]()

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

### Answer Yes, you can receive post-call analysis data via webhook. [(1) ]() The webhook payload for the

call_analyzed

event includes the

call_analysis

field with your data:

json
{
  "event_type": "call_analyzed",
  "call": {
    "call_analysis": {
      "call_summary": "The agent called the user to ask question about his purchase inquiry...",
      "in_voicemail": false,
      "user_sentiment": "Positive",
      "call_successful": true,
      "custom_analysis_data": {}
    }
  }
}

, [(2) ]() Key points: - Post-call analysis is delivered in the

call_analyzed

webhook event (the third webhook after

call_started

and

call_ended

) [(1) ]() - Your custom extraction data appears in the

custom_analysis_data

object [(2) ]() - Fields will not be populated for calls that were not connected or where no conversation took place—check whether the field exists before using it [(1) ]()

​ To learn more, see the sources I considered: [[1] Consume the analysis data](https://docs.retellai.com/features/post-call-analysis-consumption) [[2] Get Call](https://docs.retellai.com/api-references/get-call) ​

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

### Answer The phone number used for account verification/MFA cannot be changed directly from the dashboard. [(1) ]() To update your account verification phone number: Contact [support@retellai.com](support@retellai.com) and request the MFA phone number change. [(2) ]() , [(1) ]() Only Retell support can update MFA phone numbers for security reasons. [(2) ]() Note: If you're looking to update a Retell phone number assigned to an agent (not your account MFA number) , that's different—you can manage those in the Phone Numbers tab in your dashboard or via the Update Phone Number API. [(3) ]()

​ To learn more, see the sources I considered: [[1] Change Phone number](https://community.retellai.com/t/change-phone-number/440) [[2] team member management](https://discord.com/channels/1186424376300679209/1400903749316247586) [[3] Update Phone Number](https://docs.retellai.com/api-references/update-phone-number) ​

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