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Voice AI

Deploy AI agents that make and receive phone calls. 4Geeks Voice AI uses VAPI for telephony, ElevenLabs for voice synthesis, and Deepgram for speech-to-text — creating natural-sounding AI phone agents.

Overview

Voice AI capabilities:

  • Inbound Calls — AI answers incoming calls 24/7
  • Outbound Calls — AI makes calls for campaigns, follow-ups, reminders
  • Phone Provisioning — Get dedicated phone numbers for your agents
  • Calling Campaigns — Bulk outbound call campaigns with CSV upload
  • Call Analytics — Monitor call duration, outcomes, and transcripts

Setting Up Voice AI

Step 1: Choose Voice Channel

When creating an agent:

  1. Open the Agent Studio
  2. At the Channel step, select Phone
  3. The voice AI configuration options appear

Step 2: Provision a Phone Number

  1. Click Connect Phone Number
  2. Choose a number:
  3. Search for a new number — By country code and area code
  4. Use an existing number — From your account
  5. Confirm the number assignment
  6. The number is linked to your agent

Step 3: Configure Voice Settings

Setting Description Options
Voice Provider Text-to-speech engine ElevenLabs, PlayHT
Voice Specific voice selection Multiple voices per provider
Transcription Speech-to-text engine Deepgram (default)
Language Call language English, Spanish, Portuguese, French
First Message Opening greeting Custom message
End Call Phrase How the agent ends calls Configurable

Step 4: Configure AI Model

Setting Description Default
LLM Provider Language model OpenAI
Model Specific model gpt-4o-mini
System Prompt Agent behavior instructions Auto-generated or custom
Temperature Response creativity 0.7

VAPI Integration

4Geeks Voice AI is powered by VAPI (Voice API):

What VAPI Provides

Feature Description
Telephony Phone number provisioning and call routing
Assistant Management Create and configure AI assistants
Tool Execution Server-side tool calls during conversations
Call Recording Record and store call audio
Transcripts Real-time and post-call transcripts

VAPI Assistant Configuration

When you deploy a voice agent, 4Geeks automatically creates a VAPI assistant with:

  • Your system prompt
  • Selected voice and transcription settings
  • Tool configurations (calendar, CRM, etc.)
  • Phone number assignment

Server-Side Tools

Voice agents can execute tools during calls:

Tool Description
Calendar Booking Schedule appointments during the call
CRM Lookup Look up customer information
CRM Update Update records after the call
Transfer Call Transfer to a human agent
End Call Politely end the conversation

Tools are executed via the vapi-tool-handler edge function.

Outbound Calling Campaigns

Create and manage bulk outbound call campaigns.

Creating a Campaign

  1. Navigate to the Campaigns tab in AI Agents
  2. Click Create Campaign
  3. Configure:
  4. Campaign Name — Descriptive name
  5. Agent — Which voice agent to use
  6. Phone List — Upload a CSV of phone numbers
  7. Schedule — When to make calls (immediate or scheduled)
  8. Concurrency — How many calls simultaneously
  9. Click Launch Campaign

CSV Format for Phone Lists

phone_number,customer_name,notes
+15551234567,John Doe,Follow up on quote
+15559876543,Jane Smith,Appointment reminder
+15555555555,Bob Wilson,Payment reminder

Campaign Dashboard

Monitor campaign performance:

Metric Description
Total Calls Number of calls in the campaign
Completed Calls that reached a person
No Answer Calls that went to voicemail or weren’t answered
Failed Calls that failed (invalid number, etc.)
Average Duration Mean call length
Success Rate Percentage of completed calls

Campaign Status

Status Description
Pending Campaign created, not yet started
Running Calls are being made
Paused Campaign temporarily stopped
Completed All calls have been attempted
Failed Campaign encountered an error

Campaign Controls

  • Pause — Stop making new calls (in-progress calls continue)
  • Resume — Continue from where the campaign paused
  • Cancel — Stop the campaign entirely
  • View Logs — See individual call results

Call Logs

Each call in a campaign is logged:

Field Description
Phone Number Number called
Status Completed, No Answer, Failed
Duration Call length in seconds
Transcript Full conversation transcript
Recording Call recording (if enabled)
Outcome Result summary
Timestamp When the call was made

Phone Number Management

Viewing Connected Numbers

  1. Navigate to the Channels tab
  2. View all connected phone numbers:
Number Agent Status Country
+1 (555) 123-4567 Sales Agent Active US
+506 2222-3333 Receptionist Active CR

Disconnecting a Number

  1. Navigate to Channels
  2. Find the phone number
  3. Click Disconnect
  4. Confirm

The number is released and can be reassigned later.

Call Quality

Voice Synthesis

ElevenLabs provides natural-sounding voices:

  • Multiple voice options per language
  • Adjustable speed and pitch
  • Emotional tone control
  • Low latency streaming

Speech Recognition

Deepgram provides accurate transcription:

  • Real-time transcription during calls
  • Support for accents and dialects
  • Punctuation and formatting
  • Multi-language support

Latency Optimization

The voice AI stack is optimized for low latency:

Component Typical Latency
Speech-to-Text 300ms
LLM Processing 500ms
Text-to-Speech 400ms
Total ~1.2 seconds

Billing

Voice AI calls consume tokens from your agent balance:

Component Cost
Per-minute charge Varies by destination country
LLM tokens Standard token pricing
Voice synthesis Included in per-minute charge
Transcription Included in per-minute charge

Auto-refill ensures your agents never stop mid-call.

Best Practices

  1. Write clear prompts — Voice agents need concise, conversational prompts
  2. Set expectations — The first message should clearly state it’s an AI
  3. Test thoroughly — Use the playground before deploying to production
  4. Monitor transcripts — Review call logs to improve agent performance
  5. Start small — Begin with a small campaign, then scale up

What’s Next


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