Build
An agent is one prompt plus a set of settings - no flow charts to drag. One agent can answer hundreds of phone numbers, each with its own business details.One prompt, one agent
Describe the business, the rules and what to do in each situation. No node graphs to maintain.
Scenarios, not flow charts
Write “if the caller asks X, do Y” in plain English. The same control, none of the setup.
One agent, many businesses
Each number carries its own profile, voice, calendar and webhook. Built for agencies and SaaS from day one.
Call centre features
Cold and warm transfer, keypad input, phone-menu navigation on outbound, and wait handling.
Bookings during the call
Cal.com or Google Calendar, checked and booked while the caller is on the line - per phone number.
Custom functions
The agent calls your own API mid-conversation to look something up or write it back.
Voice and SMS on one number
The same number answers the phone and replies to texts, with separate instructions for each.
The agent knows the caller
Name, email and reference from earlier calls are in front of the agent before it speaks.
Deploy
Your numbers stay in your own carrier account. Nixflex never resells them and never marks them up.Bring your own carrier
Twilio or Telnyx, in your account. Each of your customers can bring their own - you keep the billing relationship.
Outbound and campaigns
One call over the API, or a whole list with concurrency control and a sending window.
Calls from a browser
Put a voice agent on your website - the same agent, no phone number needed.
SMS campaigns
Send to a list and let the agent handle the replies that come back.
Monitor
Listen to a live call
Follow a call in progress from a phone or tablet. Possible because the engine is ours, not a reseller’s.
Post-call analysis
A written summary, how the caller sounded, whether the call succeeded, and any fields you define.
Webhooks
Call events sent to your system the moment a call ends. No polling.
Built-in reliability
Backup model, speech engine and voice engine take over mid-call if a provider fails.
Your data
Transcripts and recordings
Every call, with the audio recorded by your carrier or by the engine - your choice, per number.
Your own storage
Send recordings straight to your own S3-compatible bucket. Nixflex keeps only the path.
Deleted after 90 days
Call data is removed automatically, and you can erase one caller or one call on request.
Push it anywhere
GoHighLevel, Slack, Zapier, Make, or your own endpoint - configured per phone number.
Developer friendly
Build entirely in the dashboard, or go fully programmatic. Nothing is dashboard-only.REST API
Every capability over HTTPS and JSON, with an OpenAPI spec.
SDKs
Typed Node.js and Python clients with retries built in.
CLI
The whole API from a terminal.
npx nixflexMCP server
Run your account from Claude Desktop, Cursor or VS Code.
What is an AI phone agent?
An AI phone agent is software that answers a phone number and holds a spoken conversation, instead of playing a menu. It understands what the caller says, replies in a natural voice, and takes action - booking, transferring, texting. Callers speak normally; there is no “press 1 for opening hours”.How does a call actually work?
Your number points at the Nixflex engine. When someone calls, their speech becomes text, the agent decides what to say and do, and a natural voice speaks the reply - the whole loop in about a second, with the first audio in roughly half of one. Interruptions, silence, language switching and call endings are handled by the engine, so your instructions only cover your business.Do I need to know how to code?
No. In the dashboard you write the agent’s instructions, connect your number and you are live in about five minutes. Developers get identical features over the API, SDKs, CLI and MCP. The only difference between the two paths is how you set things up.What does it cost?
Pay as you go from 0.09. Texts are billed by your own carrier at their rate. No subscription, and switching features on costs nothing. New accounts start with free credit. See Pricing.Who is it for?
Developers and SaaS
Put phone agents inside your product. Every customer brings their own carrier account and numbers.
Agencies
One agent template across many client numbers, each with its own calendar, CRM and settings.
Businesses
Clinics, salons, restaurants, garages and service businesses - a phone agent without building anything.
Your own products
Full control and the lowest cost, because you own the numbers and the account.
What does it not do?
Nixflex does not sell phone numbers - you bring your own carrier, which is also why you keep control of them. There is no visual flow builder, by design: scenarios are written as sentences. A knowledge base is not available yet, so facts go in the prompt or come from a custom function during the call. And an agent only knows what you tell it - give it your prices and hours, and it will take a message rather than guess at anything else.Next steps
Quickstart
Developer path - first call in five minutes.
For businesses
No-code path - connect a number in the dashboard.