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This guide walks you through connecting your Zadarma phone numbers using SIP trunking. Zadarma offers two connection types — PBX and SIP Direct — and the setup differs slightly for each.
Which type do you have? If you use Zadarma’s virtual PBX with extensions (e.g., 100, 101), you have PBX. If you use a standalone SIP account without a PBX, you have SIP Direct.
Select your connection type below and follow the steps:

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Step 1: Gather Your SIP Credentials

  1. Log in to your Zadarma Dashboard
  2. Go to My PBX → Extensions
Zadarma My PBX Extensions
  1. Find your extension and note these details:
Extension: e.g., 510000-100
Server address: pbx.zadarma.com
Username: Your extension username (e.g., 510000-100)
Password: Your extension password
Phone number: Your phone number (e.g., +521151900966)
Zadarma PBX Extension Settings

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Step 2: Set Up External Server (for inbound calls)

To receive inbound calls, you need to configure an External Server in Zadarma that forwards incoming calls to the platform’s SIP server.
  1. In your Zadarma Dashboard, go to Settings → Virtual phone numbers
Zadarma Settings Virtual phone numbers
  1. Find the number you want to connect and click the gear icon to open its settings
Zadarma Settings Virtual phone numbers Gear Icon
  1. Click External Server and enable the SIP URI checkbox
Zadarma PBX External Server SIP URI configuration
  1. Enter the SIP server address using your phone number with the + prefix:
+YOUR_PHONE_NUMBER@5wed79aeavr.sip.livekit.cloud
For example, if your number is +551151900966:
+521151900966@5wed79aeavr.sip.livekit.cloud
Zadarma PBX Server Address configuration
  1. Click Show IP below the server address to reveal Zadarma’s IP addresses (e.g., 185.45.152.216, 185.45.155.33)
Zadarma PBX Show IP button
Zadarma PBX IP addresses revealed
Save these IPs — you will need them in Step 3 when configuring inbound authorization in the platform.
PBX users must use the phone number with + in the External Server address. Using the PBX extension number (e.g., 533177-100) will not work for inbound calls.

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Step 3: Import Numbers to the Platform

Now import the number so the platform knows how to route calls.
  1. Go directly to the Phone Numbers page in your dashboard: https://app.autocalls.ai/phone-numbers If it takes you to the login page, log in first — it will automatically redirect you to the Phone Numbers page.
  2. Click “Integrate SIP trunk” (top-right corner of the page)
Import numbers via SIP trunk
  1. Fill in your phone number and SIP credentials:
Phone number: e.g., +551151900966
Username: Your PBX extension (e.g., 533100-100)
Your SIP Extension: Your phone number (e.g., +551151900966)
Password: Your PBX extension password
PBX users: The Username is your PBX extension (e.g., 533100-100). The “Your SIP Extension” field must be your phone number — this must match the number you used in the External Server address in Step 2.
PBX Extension credentials
  1. Enter the Server address for outbound calls:
pbx.zadarma.com
Zadarma outbound server address
  1. Select the Authorization type. Select IP and add the Zadarma IP addresses you noted earlier from Show IP in Step 2.
Zadarma IP Authorization
  1. Select the country where your SIP trunk is located.
SIP Country selection

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Step 4: Verify Setup

  1. Make a test call to your number
  2. Check that the AI assistant answers
  3. Use the test call feature to verify outbound calling

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Security Requirements

Your SIP credentials need to be secure:
  • Username: Your extension number or provider-supplied username
  • Password must have:
    • 12 or more characters
    • Numbers
    • Upper and lowercase letters
    • Special characters recommended

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Call Transfer Limitations

Zadarma does not support SIP REFER, which means standard cold transfer will not work out of the box. Warm transfer works automatically — the platform handles it via SIP INVITE.For cold transfer, you can use the Custom SIP Transfer option in your assistant’s transfer settings. Set the custom SIP URI to:
sip:+DESTINATION_NUMBER@sip.zadarma.com
For example: sip:+15557654321@sip.zadarma.comMake sure the number is in international E.164 format with the + prefix. Do not use tel: URI format.

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Common Issues

  • Check your External Server address — make sure the format matches your connection type:
    • PBX: +YOUR_PHONE_NUMBER@5wed79aeavr.sip.livekit.cloud (phone number with +)
    • SIP Direct: YOUR_EXTENSION@5wed79aeavr.sip.livekit.cloud (extension number)
  • Verify the External Server is enabled in Zadarma’s settings
  • Check that the “Your SIP Extension” field in the platform matches: phone number for PBX, extension for SIP Direct
  • Check the Server address — it should be pbx.zadarma.com for PBX or sip.zadarma.com for SIP Direct
  • Verify your credentials — make sure the username and password match what’s shown in your Zadarma SIP settings
  • Check your Zadarma balance — outbound calls require sufficient credit
Zadarma does not support SIP REFER. To enable cold transfer:
  1. Go to your assistant’s Transfer Phone Call tool settings
  2. Enable “Custom SIP transfer” (under Advanced)
  3. Set the SIP URI to sip:+DESTINATION_NUMBER@sip.zadarma.com
If cold transfer still fails, verify the destination number is in international format with +.
  • PBX is recommended if you need multiple extensions, call routing rules, IVR menus, or other PBX features in Zadarma
  • SIP Direct is simpler if you just need a single number connected without PBX features
Both work equally well for inbound and outbound AI calls.
Need help setting up? Our support team specializes in helping customers integrate their phone systems. We’ll guide you through the entire process, ensuring a smooth setup with your specific phone system configuration.