How to Build Custom Call Flows with Callr

Callr lets you design call flows in a low-code builder, trigger them from events in your existing stack, and run them serverless on Callr's own carrier network. You branch on caller intent, route to the right agent or AI, and escalate to a human when it matters. This fits teams that want voice, SMS, and AI agents embedded in a product without building telecom infrastructure — the same platform Callr says handles 2.5M+ calls daily for 300+ companies across 220+ countries.

What a Callr call flow actually is

A call flow is the logic that runs between a call arriving and an outcome being recorded. On Callr it covers:

• Design — build the flow in a low-code interface rather than writing telephony code from scratch.
• Trigger — start the flow on any event in your stack (an inbound call, an SMS reminder, a CRM change).
• Branch and route — split on caller intent, send the call to a specific agent, or escalate to a human.
• Understand — transcribe, summarise, and detect sentiment as part of the flow.
• Extend — plug in any LLM you choose for the AI steps.
• Run — execute serverless on Callr's infrastructure, on the network Callr owns.

The "owns its carrier network" point matters for flow design: because Callr carries the conversation itself, the call data (CDR, transcript, sentiment, intent, source) is available to the flow rather than being lost in a phone bill.

Step-by-step: building a flow

1. Start from the outcome you want

Decide what the flow must produce before you open the builder. Callr's own example is a real-estate scenario: a caller says "I'm looking for a 2-bedroom flat, for a budget of €600,000." The flow's job is to extract name, email, and intent, then act on it.

2. Design the flow in low-code

Lay out the steps as a sequence of blocks — greeting, question, AI extraction, branch, action. Callr positions this as "build flows in hours, not months," so expect to assemble logic from components rather than code each state.

3. Define the trigger

Flows are triggered on events in your stack, not only on inbound calls. The same flow can be kicked off by an SMS reminder or another system event — Callr's framing is "built once, run everywhere."

4. Branch on intent

Use the AI step to classify what the caller wants, then route accordingly:

• Intent = booking request → route to a sales agent or booking action.
• Intent = simple query → let the AI Voice Agent handle it.
• Intent = needs a human → escalate.

5. Plug in your LLM

Callr lets you connect any LLM you choose for the language steps. This is where extraction, summarisation, and the "AI highlight" (e.g. "Eva Carr is looking for a 2-bedroom flat, for a budget of €600,000 in Paris") are produced.

6. Push results out

Every event can be pushed into your CRM, BI, or analytics stack via native connectors or webhooks. In the worked example, the extracted name and email become a contact, and the summary becomes a note.

7. Verify

Confirm the flow end-to-end: place a test call, check that the transcript, sentiment, intent, and source appear as expected, and that the record lands in your CRM/BI. If a field is missing, the branch or extraction step is the usual culprit.

What you get out of each call

Callr contrasts its output with a standard phone setup:

This is the practical reason to build flows on Callr rather than a plain voice API: the flow's output is structured data, not just a completed call.

Channels and reach

A single API covers voice, SMS, and email across 220+ countries, so a flow can mix channels — for example, an SMS reminder that triggers a voice flow, or a call that ends with an SMS containing matches ("Hello Eva, we found 2 matches. Click here to check them out.").

Where this fits

Build custom call flows on Callr if you need:

• Voice and SMS embedded in your own product via one API.
• Intent-based routing and AI handling without managing telecom infrastructure.
• Call data flowing into CRM, BI, and ad platforms automatically.

Look elsewhere if you only need basic click-to-call with no analytics, or if you require a fully code-first telephony stack rather than a low-code builder.

To start, Callr offers a free getting-started path and a demo booking; current pricing and plan limits are listed on its pricing page.