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Cartesia supports three ways to connect phone numbers to your agents: Cartesia-provisioned numbers, numbers imported from Twilio, and numbers connected through your SIP carrier. Agent calling rates apply to all three options. Cartesia charges an additional telephony fee only when you use a Cartesia-provisioned number.

Cartesia numbers

Provision US numbers from Cartesia.

Twilio

Import numbers from your Twilio account.

SIP trunk

Connect numbers from your SIP carrier.

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Manage numbers

View and manage every number on the Phone Numbers page in the Playground or through the Phone Numbers API.
Phone numbers page listing numbers in the Playground

Phone numbers in the Playground

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Assign an inbound agent

Assigning a phone number to an agent routes inbound calls on that number to the agent. A number is assigned to one agent at a time, and an agent can have several numbers.
  1. Open the phone number’s detail page.
  2. In the Agent card, search for and select your agent.

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Outbound calls

Any number on your account can place outbound calls, whether or not it is assigned to an agent. Pass its ID as from_number_id when you place an outbound call.

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Delete a number

Deletion behavior depends on the provider:
  • Cartesia number: Unassign it first. Deletion releases the number permanently.
  • Twilio number: It can be deleted while assigned to an agent. Cartesia disconnects the agent and attempts to clear the Twilio webhook, but leaves the number in Twilio. See Remove a Twilio number.
  • SIP trunk number: Unassign it first. Deletion removes it from Cartesia and detaches it from the trunk.
Deleting a number leaves its provider intact. Delete all linked numbers before deleting a provider.