Most voice platforms make you build a visual flow chart - dragging boxes and drawing arrows for every possible turn in a call. Nixflex does not work that way, and you do not need it to.
You control the entire conversation by writing scenario rules in plain English inside your prompt. The agent reads them and follows them. This gives you the same control a flow builder offers, with none of the setup.
The pattern: “if this, do that”
Every scenario rule follows one simple shape:
If the caller does or says something, then respond or act in a specific way.
A few examples:
If the caller asks about prices, tell them a check-up is 50 pounds and a cleaning is 70 pounds.
If the caller asks to speak to a person, transfer them to reception.
If you do not know the answer, say you will have someone call them back. Never make up information.
Each rule is one line. Stack as many as you need, and you have described the whole call - without a single diagram.
A full example
Here is a complete scenario block for a dental clinic agent. Drop a section like this into your prompt and the agent will handle the call exactly as written:
RULES & SCENARIOS:
- If the caller wants to book an appointment, collect their full name and
preferred day, then use the booking function to reserve the slot.
- If the caller asks about prices, tell them a check-up is 50 pounds and a
cleaning is 70 pounds.
- If the caller wants to cancel or reschedule, take their full name and the
appointment day, then offer to have reception call them back.
- If the caller asks to speak to a human, or sounds upset, transfer to reception.
- If the caller asks something not covered here, say you will pass the message
on and have someone call them back. Never invent an answer.
- Before ending any call, confirm any booked day and time back to the caller.
Multi-step flows
For anything with several steps, write the steps in order. The agent moves through them naturally:
When booking an appointment:
- Ask for the caller’s full name.
- Ask which day they would prefer.
- Repeat the day back to confirm it is correct.
- Use the booking function to reserve the slot.
- Tell the caller the appointment is confirmed.
The agent will not skip a step or jump ahead, because you have written the order explicitly.
Vague rules vs reliable rules
The agent can only follow what you actually write. Be specific.
Vague (less reliable)
Handle cancellations.
Specific (reliable)
If the caller wants to cancel, take their full name and the appointment day,
confirm the details back to them, then offer to have reception call to rebook.
If a behaviour matters, spell it out. If it is not written, do not expect it to happen the same way every time.
Combine rules with actions and functions
Scenario rules become powerful when they trigger your actions and custom functions:
If the caller confirms the booking, send them a text with the details:
[SEND_SMS: Your appointment is confirmed for the date and time we agreed.]
If the caller asks whether a slot is free, use the availability function to
check before answering.
The rule decides when; the action or function does the work.
You do not need to write rules for interruptions, silence, voicemail, or
language switching - the platform handles those for you. Spend your rules on
business logic: what to say, what to ask, and what to do.
Make your most important rules reliable
The agent follows clear rules almost every time. For the rules you cannot afford to get wrong - a required disclaimer, a “never do X” boundary - give them the best chance to stick:
- State them explicitly and keep them near the top of your prompt.
- Keep each critical rule short and direct - one instruction, not a paragraph.
- Test the scenario on a real call before going live.
A written rule guides the agent; it is not a hard technical lock. For
must-never and must-always rules, keep them simple, place them early, and
always test them before launch.
