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PhoneConnect a Zadarma Number through SIP

Connect a Zadarma Number through SIP

Connecting a supported Zadarma number as an External SIP number lets your Versafy Voice Agent answer calls to that number and use it for outgoing calls. This is useful when you want to keep ownership, billing, and number management in your own Zadarma account while using Versafy for AI-powered calls.

Do not purchase a Ukrainian number from Zadarma for this connection. Ukrainian Zadarma numbers are not currently supported by Versafy. You can use this guide with supported Zadarma numbers from other countries. If you are unsure whether a specific country or number type is supported, contact info@versafy.ai before purchasing it.

With this connection, you can use the number for:

  • inbound customer calls answered by one Versafy Voice Agent;
  • individual outbound calls from a Voice Agent;
  • outbound Campaigns, when available for your workspace;
  • call history in Call Logs & Recordings.

External SIP inbound-flow limitation: An External SIP number can be assigned only to an active AI Only Inbound Call Flow without human handover. It cannot use operator routing, schedules, announcements, or voicemail. See Inbound Call Flows.

Before you begin

Prepare the following:

  • a Zadarma account with enough balance to purchase and use a number;
  • any identity, address, or business documents required for the selected country and number type;
  • access to Zadarma’s Cloud PBX and its extension settings;
  • permission to manage Phone Numbers and Inbound Call Flows in Versafy;
  • an active Voice Agent;
  • a password manager for the PBX extension password.

Number availability, supported features, documentation requirements, and charges vary by country. Review the current terms shown by Zadarma before purchasing.

Use a PBX extension, not a static-IP trunk

This guide uses a Zadarma Cloud PBX extension with a username and password. It is the appropriate connection type for Versafy’s External SIP form and supports both incoming forwarding and authenticated outgoing calls.

Do not select Settings → SIP Connection → Add a SIP Trunk for this setup. Zadarma uses that name for an IP-authorized connection that requires your own fixed public IP address. It does not use the credential-based setup described here. Zadarma explains the difference in What is a SIP trunk? .

Setup overview

You will complete the connection in this order:

  1. Buy a voice number in Zadarma.
  2. Create or select a Zadarma Cloud PBX extension.
  3. Import the number into Versafy with the extension’s SIP credentials.
  4. Copy the inbound SIP URI generated by Versafy.
  5. Forward calls from the Zadarma extension to that URI.
  6. Assign the number to an AI Only Inbound Call Flow.
  7. Test inbound and outbound calls.

1. Buy a number in Zadarma

The virtual number is the public number customers call and the number your Voice Agent can present on supported outbound calls.

  1. Sign in to your Zadarma account .
  2. Open Settings → Virtual phone numbers.
  3. Choose a supported country, area, and number type. Do not purchase a Ukrainian Zadarma number for this connection.
  4. Confirm that the selected number supports incoming voice calls.
  5. Review the activation charge, recurring charge, and any usage conditions.
  6. Add funds and complete the purchase.
  7. Submit any identity, address, or business documents requested for that number.
  8. Copy the number in international E.164 format, including + and the country code—for example, +442012345678.

Activation may remain pending while Zadarma reviews documents. Wait until the number is active before testing the connection. See Zadarma’s virtual-number connection guide  if the purchase flow or requirements differ in your account.

2. Prepare a Zadarma PBX extension

The PBX extension provides the SIP address and credentials Versafy uses to place outgoing calls through your Zadarma account.

  1. In Zadarma, open My PBX → Extensions.
  2. Create an extension or select one dedicated to Versafy.
  3. Copy the extension number. It commonly has a format similar to 1234-100.
  4. Generate or reveal the extension password and store it securely.
  5. Confirm that the purchased number routes to this extension in your Zadarma PBX settings.
  6. If Zadarma offers an outbound caller-ID choice for the extension, select the purchased number.

For this connection, the outbound server is pbx.zadarma.com, the username is the complete PBX extension number, and the password is the extension password. Do not use your Zadarma website password.

Zadarma’s PBX connection examples  show where the extension username, password, and server are found. Menu labels can vary slightly with account language and interface updates.

3. Import the number into Versafy

Importing makes the Zadarma-owned number available for inbound AI calls and outbound Voice Agent calls without connecting your complete Zadarma account.

Navigation: Open Phone → Phone Numbers, select the Numbers tab, then select Add external number (via SIP).

  1. Enter a clear Label, such as Zadarma Sales Line.

  2. Enter the purchased Phone number in E.164 format, including + and the country code.

  3. Expand Inbound Configuration.

  4. Under Inbound routing / Origination URI, copy the complete SIP URI. Keep this page open because you will add the URI to Zadarma in the next section.

  5. Set inbound Media Encryption to Disabled.

  6. Leave the optional inbound number filters, source-address filters, domain list, header mappings, username, and password empty for the initial setup.

  7. Expand Outbound Configuration and enter:

    • Address: pbx.zadarma.com
    • Transport: TCP (recommended)
    • Media Encryption: Disabled
    • SIP Trunk Username: your complete Zadarma PBX extension number, such as 1234-100
    • SIP Trunk Password: the password generated for that extension

  8. Leave optional outbound headers and codecs empty for the initial setup.

  9. Select Import.

The number should now appear under Numbers and be available for outbound calls. Keep its Edit action available while you finish and test the inbound route.

4. Route incoming Zadarma calls to Versafy

Forwarding the PBX extension to Versafy’s SIP URI sends calls from your Zadarma number to the Voice Agent assigned in Versafy.

  1. Return to Zadarma and open My PBX → Extensions.
  2. Open the extension you connected to the purchased number.
  3. Next to Call forwarding and voicemail, select Enable.
  4. Choose Always active as the forwarding condition.
  5. Under Call forwarding for, select External server (SIP URI).
  6. Paste the inbound SIP URI copied from Versafy.
  7. Save the extension settings.

Zadarma’s field normally expects the destination in a format such as number@host:port;transport=tcp. If it rejects a value beginning with sip:, remove only the leading sip: and keep the number, hostname, port, and transport=tcp unchanged.

If you chose not to use Zadarma Cloud PBX, a number can instead be routed from Settings → Virtual phone numbers → gear icon → External Server. The PBX-extension method above is recommended because the same extension credentials also support outbound calls. Zadarma documents both routing choices in its external SIP forwarding example .

5. Assign an AI Only Inbound Call Flow

The inbound flow chooses which Voice Agent answers the Zadarma number.

  1. In Versafy, open Phone → Phone Numbers → Inbound Call Flows.
  2. Create a flow using the AI Only template.
  3. Select the imported Zadarma number and the Voice Agent that should answer.
  4. Review, create, and activate the flow.
  5. Return to the Numbers tab and confirm that the number shows Inbound Call Flow Attached and the intended flow name.

If you created the flow before importing the number, find the number under Numbers, choose Connect to an Inbound Call Flow, and select an active AI Only flow.

6. Test both call directions

Test incoming and outgoing calls separately. This makes it easier to identify whether a problem is in Zadarma routing, SIP credentials, or the Versafy flow assignment.

Test inbound calls

  1. Call the Zadarma number from a separate phone.
  2. Confirm that the expected Voice Agent answers with the correct opening message.
  3. Ask one normal test question, then end the call.
  4. Open Phone → Call Logs & Recordings and confirm that the call appears.

Test outbound calls

  1. Open Phone → Voice Agents.
  2. Find the active agent and select Make a call.
  3. Select the imported Zadarma number as the caller number.
  4. Enter the destination in E.164 format, including + and the country code.
  5. Answer the test call and verify two-way audio and the displayed caller number.
  6. Check Call Logs & Recordings before repeating a failed or unclear attempt.

If the call does not leave Zadarma, also check the account balance and whether the destination country is enabled for your account.

Troubleshooting

Outbound calls fail with an authentication error

Confirm that Address is pbx.zadarma.com, the username is the complete PBX extension number, and the password belongs to that same extension. Do not use the main Zadarma account password or a standard SIP login from Settings → SIP Connection with the PBX server.

If you intentionally use a standard Zadarma SIP login instead of a PBX extension, change the Address to sip.zadarma.com and use the matching SIP login and SIP password from Settings → SIP Connection.

Outbound calls fail before ringing

Check that:

  • the destination is in international format with + and the country code;
  • the Zadarma account has enough balance;
  • calling the destination country is allowed;
  • the purchased number is selected as the extension’s outbound caller ID, when that option is available;
  • the number and PBX extension remain active.

Incoming calls do not reach Versafy

Confirm that the purchased number routes to the intended PBX extension, External server (SIP URI) forwarding is enabled and always active, and the destination exactly matches the URI generated by Versafy. Then confirm that the External SIP number is assigned to an active AI Only flow.

No flow is available for the External SIP number

Only active AI Only flows without human handover are eligible. Create or activate that type of flow before assigning the number.

The call connects but audio is missing or one-way

Confirm that both inbound and outbound Media Encryption are Disabled and outbound Transport is TCP. If the provider reports an unsupported-media error, edit the number and add PCMA/8000 and PCMU/8000 under Enabled Codecs, then test again.

The wrong caller number appears

Review the outgoing caller-ID assignment for the PBX extension in Zadarma. Availability can depend on number status, country rules, and account verification. If the intended number cannot be selected, contact Zadarma support before changing Versafy settings.

You need to change the imported phone number

You can edit its label and SIP settings, but not the E.164 number itself. Disconnect it from any flow, delete the External SIP number from Versafy, and import the correct number again. Deleting it from Versafy does not release it from your Zadarma account.

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