Phone Number Assignment

Phone numbers connect your agents to the phone network. Assigning a phone number to an agent enables inbound calls (people calling the agent) and outbound calls (the agent calling people).

Why Agents Need Phone Numbers

Without a phone number, an agent can only receive calls through the website widget or browser-based test calls. With a phone number:

• Inbound calls — When someone dials the number, the call is automatically answered by the assigned agent. This is how you deploy agents as receptionists, support lines, or booking assistants.
• Outbound calls — When the agent calls a contact (manually or via a workflow), the assigned number appears as the caller ID. This is important for outbound lead qualification, follow-ups, and appointment reminders.

Where Phone Numbers Come From

Phone numbers are purchased and managed through your voice provider’s dashboard (Retell AI, Vapi, or Bland.ai). BuildVoiceAI syncs these numbers into your account during onboarding and periodically thereafter.

To purchase a phone number:

• Retell AI — Go to your Retell dashboard , navigate to Phone Numbers, and buy a number.
• Vapi — Go to your Vapi dashboard , navigate to Phone Numbers, and purchase one.
• Bland.ai — Go to your Bland dashboard , navigate to Phone Numbers, and purchase one.

After purchasing, the number will appear in BuildVoiceAI within a few minutes. You can also manually trigger a sync from Settings.

Assigning a Phone Number

There are two places to assign a phone number to an agent:

From the Agent Editor

1. Open the agent in the Agent Editor.
2. Scroll to the Phone Number field.
3. Click the dropdown to see available numbers. Only numbers that are not assigned to another agent are shown.
4. Select a number.
5. Click Save.

From the Phone Numbers Page

1. Navigate to Phone Numbers in the left sidebar.
2. Find the number you want to assign.
3. Click the agent assignment dropdown next to the number.
4. Select the agent.
5. The assignment is saved automatically.

One Number Per Agent

Each phone number can be assigned to exactly one agent at a time. If you assign a number that is already assigned to a different agent, it will be removed from the previous agent and assigned to the new one.

Agents Without Phone Numbers

An agent without a phone number can still:

• Receive calls through the website widget
• Be tested via browser test calls
• Be used for outbound calls if another number is specified at the time of calling

However, it cannot receive inbound phone calls or be used as the default caller ID for outbound calls.

Unassigning a Phone Number

To remove a phone number from an agent without assigning it to a different agent:

1. Open the agent in the Agent Editor.
2. In the Phone Number dropdown, select None (or the empty option).
3. Click Save.

The number returns to the pool of available, unassigned numbers.

Phone Number Details

On the Phone Numbers page, each number displays:

• Number — The full phone number in E.164 format.
• Provider — Which voice provider the number belongs to (Retell, Vapi, or Bland).
• Assigned Agent — The agent currently using this number, if any.
• Status — Whether the number is active and ready for calls.

Troubleshooting

Number not appearing in BuildVoiceAI

• Make sure you purchased the number through your voice provider’s dashboard.
• Try syncing manually from Settings to pull in recently purchased numbers.
• Verify the number is active in your provider’s dashboard.

Inbound calls not reaching the agent

• Confirm the number is assigned to an active agent.
• Check that the agent’s status is set to Active (not Inactive).
• Verify your voice provider account is in good standing with sufficient credits.

Outbound caller ID showing wrong number

• Outbound calls use the agent’s assigned phone number as the caller ID.
• If the agent has no phone number assigned, the provider may use a default number or block the call.
• Ensure the correct number is assigned in the Agent Editor.