JustCall AI voice agents from your call workflow
A JustCall workflow forwards callers to a Cartesia agent's number, so a Cartesia AI voice agent answers and transfers callers back to your team.
Front-line agent
Answers calls the workflow forwards and passes the rest to your team.
Instructions
Answer financing, install time and warranty questions. Transfer quote requests to the sales team's JustCall number, and callers who ask for a rep by name to that rep.
- Handoff
- JustCall team number
Connected tools
- Transfer to JustCallTransfer
What a JustCall AI voice agent can do
Open one to watch a call. The grey lines are the tools the agent calls mid-sentence.
A Forward Calls step in the number's workflow sends callers to the agent's number as an external phone number.
An IVR Menu branch sends callers who press its key to the agent, which answers product questions while other keys still reach your team.
Callers who ask for a person go to a JustCall number whose workflow rings the right team or user.
JustCall settings
These are the workflow settings for forwarding a number's callers to the agent.
- Where
- Phone Numbers, the number, Call Routing, Edit next to the workflow.
- Step
- Forward Calls, with Forward Call Settings set to Phone Number.
- Menu option
- An IVR Menu block after Incoming call, with Forward Calls under a key's branch.
- Plan
- JustCall includes the IVR in all plans.
Set it up
A phone hand-off. A JustCall workflow forwards callers to the agent's number as an external number. There is no SIP trunk between JustCall and Cartesia. Vendor details read in November 2026.
Give the agent a number
Import a number from Twilio or connect a SIP trunk number. Transfers work only on Twilio and SIP trunk numbers, not on Cartesia numbers.
Open the number's workflow
In the JustCall web app, open Phone Numbers, select the number, then Call Routing, and click Edit next to the workflow.
Forward to the agent
Click +, choose Forward Calls, set Forward Call Settings to Phone Number with the agent's number, and Save. To use a key, add the step under an IVR Menu branch. Then Publish.
Set the way back and test
Add a transfer rule in Cartesia to a JustCall number that reaches a person. Call the number, reach the agent, and ask for a person.
Before you build
Pick Phone Number, not JustCall Number
Under Forward Call Settings, choose Phone Number, then select the country code and enter the agent's number. JustCall Number is for JustCall lines.
Forwarded calls sit outside bundles
JustCall lists calls forwarded to external numbers as not included in plan bundles, so bundled minutes don't cover the leg to the agent.
Menus end after retries
After 3 invalid key presses, JustCall's IVR ends the call. Name the agent's key plainly in the greeting, such as "press 2 for questions".
Transfers are cold
The person who picks up gets the call, not the conversation. Have the agent tell the caller where it's sending them before it transfers.
Use cases for teams on JustCall
More integrations
Enterprise-grade security
HIPAA compliant
SOC 2 Type 2
GDPR
JustCall AI voice agent FAQs
Does JustCall have an AI voice agent?
Yes. JustCall's AI Voice Agent handles inbound and outbound calls, qualifies leads, books appointments and transfers to your team. To use a Cartesia agent instead, a JustCall workflow forwards callers to the agent's phone number. JustCall has no built-in Cartesia connection, so it's a phone hand-off.
Can I use my own AI agent with JustCall?
Yes, if the agent has its own phone number. A Forward Calls step in the number's workflow sends callers to it, and the agent transfers back to a JustCall number that reaches a person. A Cartesia agent calls webhook tools you define in your own systems and uses the voice and model you choose.
How do I forward JustCall calls to an AI agent?
In the JustCall web app, open Phone Numbers, select the number, then Call Routing, and click Edit next to the workflow. Click +, choose Forward Calls, set Forward Call Settings to Phone Number with the agent's number, and Save. Then Publish.
Do callers have to pick a JustCall menu option?
No. Put the Forward Calls step right after the Incoming call trigger and every call goes to the agent. Use an IVR Menu branch only when you want callers to choose, and name the agent's key plainly, because the IVR ends the call after 3 invalid key presses.
Do forwarded calls use my JustCall bundled minutes?
No. JustCall lists calls forwarded to external numbers as not included in plan bundles, so the leg to the agent is billed separately. On top of that, Cartesia charges $0.03/min, plus LLM usage and telephony, and Twilio or your SIP carrier bills the agent's number.
Get started today
Talk to an expert.
Connect with a member of our team and learn how Cartesia can help you build world-class voice experiences.
Start building.
Access our models via API and bring a voice agent into production in minutes.