Vapi integration (API)

This guide shows how to integrate Vapi with Vobiz programmatically to enable outbound calling and inbound calling. Your AI assistants can call any phone number, and inbound calls to your Vobiz number can be routed to a Vapi assistant.

Prefer the dashboard? Check out the dashboard setup guide for a visual step-by-step walkthrough.

Prerequisites

A Vobiz account with a SIP trunk
A Vapi account with a private key
A Vapi assistant - create one in the dashboard
A phone number from Vobiz (for caller ID)

Part 1: Vobiz setup

Create a SIP trunk

Create a SIP trunk in Vobiz to handle voice traffic. See the SIP trunks documentation. Save these values from the response:

sip_domain (for example, 5f3a607b.sip.vobiz.ai)
username
password

You’ll need them for Vapi configuration.

Get a phone number

Purchase a phone number for outbound caller ID or inbound calls. See the phone numbers documentation.

Part 2: Vapi setup

Get your Vapi private key

Log in to the Vapi Dashboard.
Click your profile icon (top right) and go to Settings → API Keys.
Click Create new key and copy the key.

c07947df-6ba2-4e58-92f5-35e92849f6c2

Save this key securely - you’ll use it in all API requests.

Get your assistant ID

In the Vapi Dashboard, go to Assistants.
Select your assistant (or create one) and copy the Assistant ID.

9fb6d4c5-9403-49ea-afeb-9b493d63b474

Or list assistants via the API:

curl "https://api.vapi.ai/assistant" \
  -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY"

Part 3: Connect Vobiz to Vapi (outbound)

Step 1: Create the SIP credential in Vapi

curl -X POST "https://api.vapi.ai/credential" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY" \
  -d '{
    "provider": "byo-sip-trunk",
    "name": "Vobiz Trunk",
    "gateways": [{
      "ip": "bfab10fb.sip.vobiz.ai",
      "inboundEnabled": false
    }],
    "outboundLeadingPlusEnabled": true,
    "outboundAuthenticationPlan": {
      "authUsername": "Vapi_user",
      "authPassword": "Password@123"
    }
  }'

Replace:

bfab10fb.sip.vobiz.ai → your Vobiz SIP domain
Vapi_user → your Vobiz username
Password@123 → your Vobiz password

{
  "id": "65a79bd2-c1b9-4c83-8e55-97c22c092b48",
  "provider": "byo-sip-trunk",
  "gateways": [{
    "ip": "bfab10fb.sip.vobiz.ai",
    "inboundEnabled": false
  }]
}

Save the id - this is your credential ID.

Step 2: Register the phone number

Associate your phone number with the SIP credential for caller ID.

curl -X POST "https://api.vapi.ai/phone-number" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY" \
  -d '{
    "provider": "byo-phone-number",
    "name": "Vobiz Line",
    "number": "08071387149",
    "numberE164CheckEnabled": false,
    "credentialId": "65a79bd2-c1b9-4c83-8e55-97c22c092b48"
  }'

{
  "id": "91122039-9644-47fd-a545-d865075a6941",
  "number": "08071387149",
  "status": "active",
  "credentialId": "65a79bd2-c1b9-4c83-8e55-97c22c092b48"
}

Save the id - this is your phone number ID.

Step 3: Make an outbound call

curl -X POST "https://api.vapi.ai/call/phone" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY" \
  -d '{
    "assistantId": "9fb6d4c5-9403-49ea-afeb-9b493d63b474",
    "customer": {
      "number": "+919148223344",
      "numberE164CheckEnabled": false
    },
    "phoneNumberId": "91122039-9644-47fd-a545-d865075a6941"
  }'

{
  "id": "019a0bce-0cf3-7337-a253-f65f4e9c68f4",
  "status": "queued",
  "type": "outboundPhoneCall",
  "assistantId": "9fb6d4c5-9403-49ea-afeb-9b493d63b474",
  "customer": { "number": "+919148223344" },
  "phoneNumberId": "91122039-9644-47fd-a545-d865075a6941"
}

Call initiated. The phone will ring, and when answered, your AI assistant will speak.

Verification

Check call status

View call logs in Vapi Dashboard → Calls, or via API:

curl "https://api.vapi.ai/call/019a0bce-0cf3-7337-a253-f65f4e9c68f4" \
  -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY"

Test call flow

Run Step 3 to initiate a call.
Wait for the destination phone to ring.
Answer the call.
The AI assistant will greet and speak.
Check the call transcript in the Vapi Dashboard.

Inbound calls

Route calls placed to your Vobiz number directly to your Vapi AI assistant using the API.

Caller dials Vobiz number → Vobiz SIP → Vapi SIP trunk → Vapi AI assistant

Step 1: Create an inbound SIP credential in Vapi

Create a SIP trunk credential configured for inbound only - using the Vobiz gateway IP instead of a SIP domain.

curl -X POST "https://api.vapi.ai/credential" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY" \
  -d '{
    "provider": "byo-sip-trunk",
    "name": "Vobiz Inbound Trunk",
    "gateways": [{
      "ip": "13.233.44.61",
      "port": 5060,
      "netmask": 32,
      "inboundEnabled": true,
      "outboundEnabled": false
    }]
  }'

{
  "id": "46deea29-645d-44a3-bf42-7c6ec2d4b65c",
  "provider": "byo-sip-trunk",
  "gateways": [{
    "ip": "13.233.44.61",
    "outboundEnabled": false
  }],
  "name": "Vobiz Inbound Trunk"
}

Save the id - this is your inbound credential ID (also called Trunk ID).

Want both inbound and outbound on the same trunk? Add a second gateway entry for outbound with your Vobiz SIP domain and credentials:

"gateways": [
  {
    "ip": "13.233.44.61",
    "inboundEnabled": true,
    "outboundEnabled": false
  },
  {
    "ip": "bfab10fb.sip.vobiz.ai",
    "inboundEnabled": false,
    "outboundEnabled": true
  }
]

Step 2: Get the trunk ID

If you didn’t save the ID from Step 1, retrieve it by listing all credentials:

curl -X GET "https://api.vapi.ai/credential" \
  -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY"

Find the entry with gateway IP 13.233.44.61 and outboundEnabled: false. The id field is your trunk ID.

Step 3: Configure the inbound trunk in Vobiz

Create an inbound trunk in the Vobiz Console that routes calls to Vapi:

Go to Vobiz Console → SIP Trunks → Inbound Trunk.
Click Create New Trunk.
Set Name and Transport to UDP.
Set Primary URI to <VAPI_TRUNK_ID>.sip.vapi.ai - for example, 46deea29-645d-44a3-bf42-7c6ec2d4b65c.sip.vapi.ai.
Link your Vobiz phone number to this trunk.
Click Save.

Or use the Vobiz API to create the inbound trunk programmatically - see the SIP trunks documentation.

Step 4: Register the inbound phone number in Vapi

curl -X POST "https://api.vapi.ai/phone-number" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_VAPI_PRIVATE_KEY" \
  -d '{
    "provider": "byo-phone-number",
    "name": "Vobiz Inbound Line",
    "number": "+918071387376",
    "numberE164CheckEnabled": true,
    "credentialId": "46deea29-645d-44a3-bf42-7c6ec2d4b65c",
    "assistantId": "YOUR_ASSISTANT_ID"
  }'

Replace:

+918071387376 → your Vobiz phone number
46deea29-... → your inbound credential ID from Step 1
YOUR_ASSISTANT_ID → your Vapi assistant ID

Inbound setup complete! Dial your Vobiz number - the call will route to your Vapi AI assistant automatically.

Troubleshooting

”Unauthorized” / “Invalid API key”

Vapi private key is incorrect.

Verify you copied the entire key.
Generate a new key at Vapi Dashboard → Settings → API Keys.

”Couldn’t get assistant”

Wrong assistant ID or it doesn’t exist.

Run curl "https://api.vapi.ai/assistant" -H "Authorization: Bearer YOUR_KEY" and use the correct id.
Don’t confuse credential ID with assistant ID.

”SIP authentication failed”

Vobiz credentials are incorrect.

Verify SIP domain, username, password in Vobiz Console.
Use the exact sip_domain (for example, bfab10fb.sip.vobiz.ai), not a generic sip.vobiz.ai.

Call connects but silent

Assistant configuration issue.

Verify the assistant has a “First Message” configured.
Check the assistant has a voice provider set up.
View call logs in Vapi Dashboard → Calls.

Call doesn’t connect

Use E.164 format: +919148223344.
Verify your Vobiz trunk is active in Vobiz Console.

Quick reference

Required credentials

Credential	Where to get	Used in
Vapi private key	Vapi Dashboard → Settings → API Keys	All API requests
Vobiz SIP domain	Vobiz Console → Trunks → `sip_domain`	Step 1: `gateways[0].ip`
Vobiz username	Vobiz Console → Trunks	Step 1: `authUsername`
Vobiz password	Vobiz Console → Trunks	Step 1: `authPassword`
Phone number	Vobiz Console → Numbers	Step 2: `number`
Credential ID	Step 1 response `id`	Step 2: `credentialId`
Phone number ID	Step 2 response `id`	Step 3: `phoneNumberId`
Assistant ID	Vapi Dashboard → Assistants	Step 3: `assistantId`

API endpoints

All requests require Authorization: Bearer YOUR_VAPI_PRIVATE_KEY.

Action	Method	Endpoint
Create SIP credential	POST	`https://api.vapi.ai/credential`
Register phone number	POST	`https://api.vapi.ai/phone-number`
Make outbound call	POST	`https://api.vapi.ai/call/phone`
List assistants	GET	`https://api.vapi.ai/assistant`
Get call details	GET	`https://api.vapi.ai/call/{callId}`

Common errors

Error	Cause	Fix
401 Unauthorized	Wrong Vapi private key	Verify the key in the dashboard
Assistant does not exist	Wrong assistant ID	List assistants via API
SIP auth failed	Wrong Vobiz credentials	Check Vobiz Console → Trunks
Insufficient balance	Low Vobiz credits	Add funds in the Vobiz Console
Phone format error	Missing `+` or country code	Use `+919148223344` or `09148223344`

Resources

Vobiz

Vapi

API reference
Assistants guide
Phone calling
Vapi Dashboard
Support: Vapi Discord or support@vapi.ai

AI Voice Platforms

Official SDKs

Browser & WebRTC

Vapi integration (API)

Prerequisites

Part 1: Vobiz setup

Create a SIP trunk

Get a phone number

Part 2: Vapi setup

Get your Vapi private key

Get your assistant ID

Part 3: Connect Vobiz to Vapi (outbound)

Step 1: Create the SIP credential in Vapi

Step 2: Register the phone number

Step 3: Make an outbound call

Verification

Check call status

Test call flow

Inbound calls

Step 1: Create an inbound SIP credential in Vapi

Step 2: Get the trunk ID

Step 3: Configure the inbound trunk in Vobiz

Step 4: Register the inbound phone number in Vapi

Troubleshooting

”Unauthorized” / “Invalid API key”

”Couldn’t get assistant”

”SIP authentication failed”

Call connects but silent

Call doesn’t connect

Quick reference

Required credentials

API endpoints

Common errors

Resources

AI Voice Platforms

Official SDKs

Browser & WebRTC

Documentation Index

​Prerequisites

​Part 1: Vobiz setup

​Create a SIP trunk

​Get a phone number

​Part 2: Vapi setup

​Get your Vapi private key

​Get your assistant ID

​Part 3: Connect Vobiz to Vapi (outbound)

​Step 1: Create the SIP credential in Vapi

​Step 2: Register the phone number

​Step 3: Make an outbound call

​Verification

​Check call status

​Test call flow

​Inbound calls

​Step 1: Create an inbound SIP credential in Vapi

​Step 2: Get the trunk ID

​Step 3: Configure the inbound trunk in Vobiz

​Step 4: Register the inbound phone number in Vapi

​Troubleshooting

​”Unauthorized” / “Invalid API key”

​”Couldn’t get assistant”

​”SIP authentication failed”

​Call connects but silent

​Call doesn’t connect

​Quick reference

​Required credentials

​API endpoints

​Common errors

​Resources

Prerequisites

Part 1: Vobiz setup

Create a SIP trunk

Get a phone number

Part 2: Vapi setup

Get your Vapi private key

Get your assistant ID

Part 3: Connect Vobiz to Vapi (outbound)

Step 1: Create the SIP credential in Vapi

Step 2: Register the phone number

Step 3: Make an outbound call

Verification

Check call status

Test call flow

Inbound calls

Step 1: Create an inbound SIP credential in Vapi

Step 2: Get the trunk ID

Step 3: Configure the inbound trunk in Vobiz

Step 4: Register the inbound phone number in Vapi

Troubleshooting

”Unauthorized” / “Invalid API key”

”Couldn’t get assistant”

”SIP authentication failed”

Call connects but silent

Call doesn’t connect

Quick reference

Required credentials

API endpoints

Common errors

Resources