What Is a Call Flow?

What it actually is

A call flow is the answer to the question "What happens when someone dials us?". Not only "who answers", but the entire path: which number was dialed, whether the caller is known, what time it is, which menu they hear, which queue they enter, who rings, and what happens if no one answers.

In telephony systems this is also called a Dial plan. In the past, with a physical PBX, this plan was a configuration file that only the technician understood. In a cloud PBX, it is built from components that have names — a number, a time group, a menu, a queue, a hunt group, a voicemail box — and each component points to the next one.

It is important to understand that there is no single "flow" for an organization. Every number has its own flow, and within each flow there are several branches: a branch for business hours, a branch for the night, a branch for VIP customers, a branch for each key in the menu. What a particular caller experiences is one branch out of this tree.

The chain of decisions — step by step

The best way to understand a call flow is to follow it through a single call. In the diagram below: a caller dials the organization's number, and the PBX goes step by step. At each step a rule is checked, and the first rule that matches decides where to continue.

1. The number dialed. Every route starts with a number. An organization can have several numbers — a main line, a donations line, a short number, a local number abroad — and each one has its own starting point. That is why the same caller can hear completely different things depending on the number they dialed.

2. Caller rule. Before anything else, the PBX checks who is calling. If the caller's number is on a list — a VIP customer, a supplier, a manager — the call leaves the regular route and goes straight to its own destination, for example the account manager. Details in Routing by Caller.

3. Time group. If the caller is not known, the time is checked. During business hours, the call continues to the menu. Outside them, a closing message plays, and from there the caller can leave a message. Details in Routing by Time.

From the menu to whoever answers

4. IVR menu. The caller hears "For service, press 2" and presses a key. Each key is a new branch in the route, and can lead to a queue, a hunt group, an extension, a message, or another menu. "Pressed nothing" and "pressed an invalid key" are branches too, and you need to decide where they lead. Details in IVR Menu.

5. Queue. Key 2 leads to the service queue. Here the caller waits: hears music, maybe a message about their place in the queue, until an agent becomes free. The queue has its own rules — the maximum wait time, and what happens when that time runs out. Details in Call Queue.

6. The agents. When an agent becomes free, the queue rings them according to the chosen distribution method: everyone at once, in order, or whoever has been free the longest. Instead of a queue you can also use a hunt group, which rings in layers: first two people, then three more.

7. Last destination. What happens if nobody answered? The queue wait time ran out, all the agents are busy, or it is after hours. This is where the last destination comes in, and usually it is a voicemail box whose messages arrive by email. A good route always ends somewhere the caller can do something — not in endless ringing or a hang-up.

Notice that in the diagram there is more than one way to reach the voicemail box: both from the closing message and from the queue after the wait time expired. This is very common — one destination can serve several branches.

"The first rule that matches" — why it matters

The principle that holds the whole route together: at each step the rules are checked in order, and the first one that matches decides. The rules after it are not checked at all. This sounds technical, but it explains most surprises.

Example. You set a VIP rule for a big customer, sending them straight to the account manager. You also set that at night all calls go to a closing message. The customer calls at eleven at night — and reaches the account manager's extension, which rings in an empty room. Why? Because the caller rule is checked before the time rule, and it matched first.

The solution is not to cancel the rule but to complete it: set the customer's rule to go to a small queue or a hunt group, which after hours continues to the on-duty person or to voicemail. But to think of that, you first need to see that it is happening.

Another common source of surprises is forwarding set on the extension itself. If an extension has a fixed forward to a mobile phone, a call that reached it through the menu will continue to the mobile — even if you set something else in the queue. Every component in the route can add its own decision.

Examples: three real routes

A small business in Bnei Brak. One number. During business hours — a menu with three options: orders, service, and accounting. Orders and service go to a hunt group of three employees, accounting to a single extension with a voicemail box. After hours — a message with the business hours and a general voicemail box. A simple route, seven stops.

A yeshiva with a dormitory. A main number and a menu: office, dormitory, payments, and a student's voicemail box. The dormitory respects the daily schedule: during seder it does not ring, and the caller hears a message with the contact hours. The voicemail key leads to a menu where the parent presses the number of their son's box and leaves a message. Here there are already three time groups and a two-layer structure.

A nonprofit on campaign night. A separate donations number. On campaign night — a very short menu, and key 1 leads to a large queue of volunteers. After the night — the number goes back to a regular route: a message, and the option to leave details. Same number, two completely different routes depending on the time.

How to plan a good route

1. Start from the caller, not from the PBX. Write down the five most common reasons people call, and for each one — who needs to answer.
2. Draw it on paper. The number at the top, then arrows: hours, menu, destinations. If the drawing does not fit on one page, the route is probably too complicated.
3. A plan B for every destination. An extension that does not answer, a queue that filled up, agents who left. Where does it go from there?
4. Every branch ends somewhere useful. A voicemail box, an informational message, or the person on duty. Not endless ringing.
5. Test from the outside. Call from a mobile phone in every situation: during hours, after hours, from every key, and without pressing anything.

Signs that the route needs fixing: customers say "I called and nobody answered"; messages pile up in a voicemail box that nobody checks; one employee gets most of the calls; or nobody in the organization can explain what happens to a call at eight in the evening.

Questions for self-check

• What does someone calling right now hear, and what will they hear in three hours?
• Where does a VIP customer end up at night?
• What happens when all the agents in the queue are busy for half an hour?
• Who receives the voicemail messages, and do they know they are receiving them?
• If an employee leaves tomorrow, in which places in the route does their extension appear?

If there is no immediate answer to one of the questions, this is the time to open the diagram and check.

A second example, end to end: a clinic with three doctors

The examples above are short. Here we will follow one call through a complete route of an imaginary clinic: three doctors, two secretaries, a nurse, and one number. At each stop we will write what is checked and what is decided.

Stop 1 — The number. The customer calls the main number on Tuesday at 10:40. The clinic also has a direct number for the lab, but she did not dial it, so the route is the main number's route.

Stop 2 — Caller rule. The PBX checks her number against the list of rules. The list includes the neighboring pharmacy, the lab company, and the three doctors' mobile phones. Her number is not there. On we go.

Stop 3 — Hours. "Closures" — no match. "Lunch break" (13:00–14:00) — no match. "Clinic hours" (Sun–Thu 08:00–19:00) — match. The destination: the clinic menu.

Stop 4 — Menu. "To make or cancel an appointment, press 1. For test results, press 2. For repeat prescriptions, press 3. To speak with the nurse, press 4." She presses 2 after four seconds. The destination of key 2: the "Results" queue.

Stop 5 — The queue. The "Results" queue has the two secretaries, with the distribution "whoever has been free the longest". Both are on calls. The customer hears "You are second in line", and after 50 seconds a secretary becomes free.

Stop 6 — The ring. The queue rings the secretary who has been free the longest for 15 seconds. She answers on the sixth second. Her phone screen shows "Results" and the caller's number.

Stop 7 — The last destination (not triggered). If neither secretary had answered within 4 minutes, the queue would have sent the call to the "Results" voicemail box, and the message would have been sent to the clinic's email. This time we did not get there — but the branch exists, and that is what makes the route complete.

"Why did the customer reach voicemail?" — a five-step investigation method

This is the question managers ask most often about the route. Instead of guessing, you go back through the call itself, stop by stop:

1. Find the call in the log. By the caller's number or the time. The log shows the route the call actually took: which number, which menu, which key, which queue, and who rang.
2. Check the time. Did the call come in within the time group? A call at 13:05 that landed on the break message is not a malfunction — it is the setting.
3. Check the branch. If it reached the menu, which key was pressed? "Pressed nothing" is the most common reason, and then the question is where the "no key pressed" branch leads.
4. Check who rang and for how long. If the queue rang two agents for 15 seconds each and nobody answered, the problem is with the agents (not registered, paused, away from the phone), not with the route.
5. Check forwarding on the extension. If the call reached an extension and went straight to voicemail, the extension has a forward, or "Do Not Disturb" was turned on by mistake from the phone.

Once the answer is found, the next question is not "who is to blame" but "does the route need a new branch". Voicemail after the maximum wait time at a regular peak hour means you need another agent at that hour, or an earlier callback offer.

How many routes does an organization have? — a number for each purpose

An organization with one number struggles to squeeze everything into one menu. An organization with three or four numbers builds a short, simple route for each one. This is often the decision that affects the route more than any other setting:

• Main number — a full menu, hours, queues.
• Direct line for regular customers — no menu, straight to a hunt group. Published only to those who need it.
• Donations line or information line — a short star number with a menu of two options, active around the clock.
• Advertising number — the same route as the main one, but in the log you can see exactly how many calls came from the ad.

Rule of thumb: if the main menu has an option that serves a completely different audience — parents versus suppliers, donors versus service recipients — it probably deserves its own number and its own route.