Phone calls

Phone calls aren't in the SDK yet. Call these REST endpoints from your server, with your account key and the flow's key in the headers.

#Before you begin

You need:

• A phone number attached to the flow, on its Numbers tab in the dashboard.
• Your account key and the flow key, as VOXIO_SECRET_KEY and VOXIO_FLOW_KEY environment variables.

#Call a number now

Post the two numbers to start the call:

1curl -X POST https://call.voxio.in/plivo/outbound \
2  -H "user_api_key: $VOXIO_SECRET_KEY" \
3  -H "flow_api_key: $VOXIO_FLOW_KEY" \
4  -H "content-type: application/json" \
5  -d '{
6        "from-number": "FROM_NUMBER",
7        "to-number": "TO_NUMBER",
8        "customs": { "variables": { "customer_name": "Priya" } }
9      }'

Replace the following:

• FROM_NUMBER: one of your numbers in E.164 format, such as +91XXXXXXXXXX
• TO_NUMBER: the number to call, in E.164 format, such as +91XXXXXXXXXX

The phone rings within a few seconds, and the agent speaks when it's answered. The request body takes:

from-numberE.164required

One of your numbers.

to-numberE.164required

The number to call, with its country code.

session_idstring

Your own id for the call. It comes back in the call’s webhooks.

customsobject

Overrides for this call, as for browser sessions.

#Schedule a call

To call later, post to the schedule endpoint with a time:

1curl -X POST https://call.voxio.in/plivo/outbound/schedule \
2  -H "user_api_key: $VOXIO_SECRET_KEY" \
3  -H "flow_api_key: $VOXIO_FLOW_KEY" \
4  -H "content-type: application/json" \
5  -d '{ "from-number": "FROM_NUMBER", "to-number": "TO_NUMBER",
6        "datetimezone": "01102026 1430 IST" }'

datetimezone is DDMMYYYY HHMM ZONE. This example calls at 2:30 PM IST on 1 October 2026.

#Answer incoming calls

A call to one of your numbers is answered by the flow the number is attached to. Each call is a session, with webhooks like any other.

#Next steps

• Webhooks: get each call’s transcript on your server.
• Headless sessions: see what you can put in customs.