Cartesia numbers - Cartesia Docs

Cartesia provides US phone numbers at no charge for the number itself. The number of slots depends on your subscription plan:

Plan	Phone number slots
Free	1
Pro	3
Startup	5
Scale	10
Enterprise	Custom

Slot limits apply only to Cartesia-provisioned numbers. Numbers imported from Twilio or connected through a SIP trunk do not use slots and are billed by your own provider. Cartesia-provisioned numbers have two limits:

US numbers only. Every Cartesia number is a US number.
Outbound to US only. Outbound calls can only reach US destinations, regardless of your agent’s region.

Provision a number

Playground
API

Go to Phone Numbers in the sidebar.
Click Add Number, then Cartesia Number.
Enter a name for the number.
Optionally assign an agent.

Provisioning a Cartesia number — Cartesia provisioning panel

curl -X POST "https://api.cartesia.ai/agents/phone-numbers/provision" \
  -H "X-API-Key: $CARTESIA_API_KEY" \
  -H "Cartesia-Version: 2026-08-14" \
  -H "Content-Type: application/json" \
  -d '{ "label": "My Agent Number" }'

If you have used every slot, delete an existing Cartesia number or upgrade your plan to add more.

Delete a number

Deletion is permanent. The number is released and cannot be recovered. Unassign the number from its agent first.

Playground
API

Go to Phone Numbers and open the number.
Unassign the number from its agent.
Click Delete.

curl -X DELETE "https://api.cartesia.ai/agents/phone-numbers/YOUR_PHONE_NUMBER_ID" \
  -H "X-API-Key: $CARTESIA_API_KEY" \
  -H "Cartesia-Version: 2026-08-14"

​Provision a number

​Delete a number

Provision a number

Delete a number