Register Your SIP Trunk on Bolna and Add Phone Numbers

After creating your SIP trunk on your provider (Plivo or Twilio), the next step is to register that trunk with Bolna. This tells Bolna how to connect to your provider’s gateway and which phone numbers belong to this trunk. You will do two things in this guide:

Create the trunk on Bolna with your provider’s gateway details and authentication credentials
Add your phone numbers (DIDs) so Bolna knows which numbers to route through this trunk

Prerequisites

Before you begin, make sure you have:

A SIP trunk already created on your provider (Plivo guide or Twilio guide)
Your provider gateway address (e.g., XXXX.zt.plivo.com for Plivo or bolna-trunk.pstn.twilio.com for Twilio)
Your authentication credentials: username/password for userpass auth, or provider IP ranges for ip-based auth
Your Bolna API key from the Bolna Dashboard
Your DID phone numbers that you purchased from your provider

Step 1: Create the Trunk on Bolna

Use the Create SIP Trunk API to register your trunk. The exact payload depends on your provider and authentication method. Choose the example that matches your setup:

IP-Based Authentication (e.g., Plivo, Telnyx)
Username/Password Authentication (e.g., Twilio, Zadarma, Vonage)

With IP-based auth, your provider identifies Bolna by its source IP address. You provide your provider’s IP ranges so Bolna can verify that incoming SIP requests are legitimate.

curl -X POST https://api.bolna.ai/sip-trunks/trunks \
  -H "Authorization: Bearer <your-bolna-api-key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Plivo Trunk - Production",
    "provider": "plivo",
    "description": "Plivo Zentrunk for Bolna Voice AI",
    "auth_type": "ip-based",
    "gateways": [
      {
        "gateway_address": "XXXXXXXXXXXXXXXXXXXX.zt.plivo.com",
        "port": 5060,
        "priority": 1
      }
    ],
    "ip_identifiers": [
      { "ip_address": "15.207.90.192/31" },
      { "ip_address": "204.89.151.128/27" },
      { "ip_address": "13.52.9.0/25" }
    ],
    "allow": "ulaw,alaw",
    "disallow": "all",
    "inbound_enabled": true,
    "outbound_leading_plus_enabled": true
  }'

{
  "id": "01HQXYZ789GHI012JKL",
  "name": "Plivo Trunk - Production",
  "provider": "plivo",
  "auth_type": "ip-based",
  "gateways": [
    {
      "id": "01HQXYZ222BBB222CCC",
      "gateway_address": "XXXXXXXXXXXXXXXXXXXX.zt.plivo.com",
      "port": 5060,
      "priority": 1
    }
  ],
  "ip_identifiers": [
    { "ip_address": "15.207.90.192/31" },
    { "ip_address": "204.89.151.128/27" },
    { "ip_address": "13.52.9.0/25" }
  ],
  "phone_numbers": [],
  "is_active": true,
  "inbound_enabled": true,
  "created_at": "2025-01-15T10:00:00Z"
}

Replace XXXXXXXXXXXXXXXXXXXX.zt.plivo.com with the Termination SIP Domain you copied from your provider’s console. The ip_identifiers above are Plivo’s IP ranges; check your provider’s documentation for their specific ranges.

With username/password auth, Bolna sends credentials with every outbound SIP request so your provider can verify the call is authorized.

curl -X POST https://api.bolna.ai/sip-trunks/trunks \
  -H "Authorization: Bearer <your-bolna-api-key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Twilio Trunk - Production",
    "provider": "twilio",
    "description": "Twilio Elastic SIP Trunk for Bolna Voice AI",
    "auth_type": "userpass",
    "auth_username": "bolna_trunk",
    "auth_password": "<your-credential-password>",
    "gateways": [
      {
        "gateway_address": "bolna-trunk.pstn.twilio.com",
        "port": 5060,
        "priority": 1
      }
    ],
    "allow": "ulaw,alaw",
    "disallow": "all",
    "inbound_enabled": true,
    "outbound_leading_plus_enabled": true
  }'

{
  "id": "01HQXYZ123ABC456DEF",
  "name": "Twilio Trunk - Production",
  "provider": "twilio",
  "auth_type": "userpass",
  "auth_username": "bolna_trunk",
  "gateways": [
    {
      "id": "01HQXYZ111AAA111BBB",
      "gateway_address": "bolna-trunk.pstn.twilio.com",
      "port": 5060,
      "priority": 1
    }
  ],
  "phone_numbers": [],
  "is_active": true,
  "inbound_enabled": true,
  "created_at": "2025-01-15T10:00:00Z"
}

Replace bolna-trunk.pstn.twilio.com with the Termination URI you configured on your provider. Replace bolna_trunk and <your-credential-password> with the credentials you created.

Save the id field from the response. This is your Trunk ID and you will need it for every subsequent API call: adding phone numbers, mapping agents, and making calls.

Step 2: Add Phone Numbers

Register the DID phone numbers you have already purchased on your SIP provider (from Plivo or Twilio). Bolna does not provision numbers, it needs to know which of your provider numbers to route through this trunk for inbound matching and outbound caller ID. Use the Add Phone Number API for each number:

curl -X POST https://api.bolna.ai/sip-trunks/trunks/<trunk-id>/numbers \
  -H "Authorization: Bearer <your-bolna-api-key>" \
  -H "Content-Type: application/json" \
  -d '{
    "phone_number": "919876543210",
    "name": "Main Support Line"
  }'

{
  "id": "01HQNUMBER111222333",
  "phone_number": "919876543210",
  "byot_trunk_id": "01HQXYZ123ABC456DEF",
  "telephony_provider": "sip-trunk",
  "created_at": "2025-01-15T10:05:00Z"
}

Save the id from the response. This is the Phone Number ID that you will use when mapping this number to an AI agent for inbound calls, and when specifying the from_number for outbound calls.

Adding Multiple Numbers

Repeat the API call for each DID number you want to add. Each number receives its own unique id:

# Example: adding a second number
curl -X POST https://api.bolna.ai/sip-trunks/trunks/<trunk-id>/numbers \
  -H "Authorization: Bearer <your-bolna-api-key>" \
  -H "Content-Type: application/json" \
  -d '{
    "phone_number": "+14158675309",
    "name": "US Sales Line"
  }'

Phone number format: Bolna stores the number exactly as you provide it and performs flexible matching (with and without the + prefix) for inbound calls. Use a consistent format across your configuration.

Step 3: Verify Your Trunk

After creating the trunk and adding numbers, verify that everything is configured correctly. Use the Get SIP Trunk API to check your trunk:

curl -X GET https://api.bolna.ai/sip-trunks/trunks/<trunk-id> \
  -H "Authorization: Bearer <your-bolna-api-key>"

Confirm the following fields in the response:

Field	Expected Value	What It Means
`is_active`	`true`	Trunk is active and ready for calls
`inbound_enabled`	`true`	Trunk can receive inbound calls
`gateways`	Your gateway address	Gateway is correctly configured
`phone_numbers`	Your added numbers	All DIDs are registered

You can also list all phone numbers on the trunk:

curl -X GET https://api.bolna.ai/sip-trunks/trunks/<trunk-id>/numbers \
  -H "Authorization: Bearer <your-bolna-api-key>"

Field Reference

Here is a complete reference of all fields you can use when creating a trunk:

Field	Type	Required	Default	Description
`name`	string	Yes		Human-readable label for the trunk. Must be unique.
`provider`	string	Yes		SIP provider: `"twilio"`, `"plivo"`, `"zadarma"`, `"telnyx"`, `"vonage"`, `"custom"`
`description`	string	No	`null`	Optional description for your internal reference
`auth_type`	string	Yes		`"userpass"` (username/password) or `"ip-based"`
`auth_username`	string	If userpass	`null`	SIP username for authentication
`auth_password`	string	If userpass	`null`	SIP password for authentication
`gateways`	array	Yes		At least one gateway with `gateway_address` (required), `port` (default 5060), `priority` (default 1)
`ip_identifiers`	array	If ip-based	`[]`	List of `{ "ip_address": "..." }` objects in CIDR notation
`allow`	string	No	`"ulaw,alaw"`	Comma-separated codecs to allow. Always include `ulaw`.
`disallow`	string	No	`"all"`	Comma-separated codecs to block
`inbound_enabled`	boolean	No	`false`	Set to `true` to receive inbound calls
`outbound_leading_plus_enabled`	boolean	No	`true`	Prepend `+` to outbound dialed numbers (required by Twilio)
`rtp_symmetric`	boolean	No	`true`	Symmetric RTP for NAT traversal. Keep as `true`.
`force_rport`	boolean	No	`true`	Force responses to source port. Keep as `true`.
`qualify_frequency`	integer	No	`60`	SIP OPTIONS keepalive ping interval in seconds. Set to `0` to disable.

Next Steps

Your trunk is registered and phone numbers are added. Now configure how calls are handled:

Receive Inbound Calls

Map your phone numbers to AI agents so they answer incoming calls

Make Outbound Calls

Place outbound calls from your trunk numbers using AI agents

Quickstarts

Phone Numbers & Calling Setup

Outbound Calling

Inbound Calling

Managing Live Calls

Prompting & Personalization

Tools & Function Calling

Post-Call & Analytics

No-Code & Automation

SIP Trunking Guide

Integrations

Register Your SIP Trunk on Bolna and Add Phone Numbers

Prerequisites

Step 1: Create the Trunk on Bolna

Step 2: Add Phone Numbers

Adding Multiple Numbers

Step 3: Verify Your Trunk

Field Reference

Next Steps

Receive Inbound Calls

Make Outbound Calls

​Prerequisites

​Step 1: Create the Trunk on Bolna

​Step 2: Add Phone Numbers

​Adding Multiple Numbers

​Step 3: Verify Your Trunk

​Field Reference

​Next Steps

Receive Inbound Calls

Make Outbound Calls

Prerequisites

Step 1: Create the Trunk on Bolna

Step 2: Add Phone Numbers

Adding Multiple Numbers

Step 3: Verify Your Trunk

Field Reference

Next Steps