Why doesn't the call go through? Common call problems, and how to check

First of all: which call isn't going through?

When people say "calls aren't going through", it can mean ten different things. Before looking for a solution, it's worth answering three short questions, because each answer points somewhere completely different:

• Which direction? An incoming call (people call you and don't get through), an outgoing call (you dial and nothing goes out), or an internal call between two extensions.
• For whom? For everyone, for one extension, or only from a certain caller.
• When? Always, or only at certain hours — in the evening, on Friday, on a holiday.

A call that never reaches anyone usually points to the number's routing. A call that doesn't reach one extension points to the phone or to the extension's settings. And a call that fails only at certain hours — is almost always a time group.

An incoming call that reaches nobody

Every number routes in three layers, in order: first by who is calling, then by time, and finally to the default destination. Common reasons for a call that disappears:

• A deleted destination. The number pointed to a queue, a menu or a routing code that was deleted — and the call was left without a destination.
• A wrong time group. "Business hours" set until 17:00 without Friday, or a holiday whose dates weren't updated this year (the dates follow the Gregorian calendar). The call goes to the night menu in the middle of the day.
• A caller rule that catches too much. A rule for the prefix 05 catches all mobiles, not just the ones you meant.
• A menu without a message or without keys. The caller hears silence, or presses a key and nothing happens.

The quick way to check: on the number card click "Call route", and the diagram shows where the call goes at every hour and for every caller. A missing destination, or one that leads somewhere unexpected, stands out right away.

The call arrives, but the phone doesn't ring

In this case the PBX did its part, and the problem is on the way to the phone itself:

• No device is registered on the extension. The phone is off, the app is closed, there's no internet, or the SIP password on the device is wrong. With no registered device, every call to the extension goes to the "Unavailable" destination — usually voicemail. See SIP registration.
• "Do not disturb" is on. See Do not disturb.
• Immediate forwarding. Every call is sent right away to another number, without ringing the extension. See call forwarding.
• Ring time too short. The phone rings for two seconds and the call already goes to voicemail.
• A queue or group with nobody to answer. No agent is logged in to the queue, or none of the extensions in the hunt group are registered.

The caller hears busy, a strange tone or a disconnect

When the caller hears something — it's a good clue to the cause:

• Busy tone. The device itself returned "busy", or the extension's quota of concurrent calls ran out. An extension has a separate destination for "busy" — you can send it to voicemail or to a queue instead of a busy tone.
• Immediate disconnect. The caller's number is blocked — on the block list, by a prefix rule or by call filtering. The call filtering service has a "Blocked calls" card that shows what was blocked in the past week and why. See blocking callers and call filtering.
• "The number is not connected" or a message from the phone company. The number itself isn't routed to us — for example during a port that hasn't finished yet. See number porting.
• The menu repeats over and over. The caller presses a key that isn't defined, and the menu plays again. It's worth setting in the menu what happens on an invalid key and on a timeout too.

An outgoing call that doesn't go out

When you dial out and nothing happens, or you hear an error message:

• The phone isn't registered. A phone that isn't registered can't dial. Its screen usually shows an error sign next to the account.
• The number is blocked for outgoing calls. Call filtering also applies to outgoing calls: a personal block and the rabbinical committee's list also block when you dial.
• A destination not included in the plan. Calls abroad or to special numbers may be blocked in the account's plan.
• A number typed incorrectly. A missing digit, or an extra prefix the phone adds on its own.

With an outgoing call it's also important to know what the other side sees. If the other side doesn't answer because they don't recognize the number, check the extension's outgoing caller ID. See caller ID.

When all the phones in the office stop at once

When no phone in the office rings and nobody can dial, the most common reason is simple: the office internet is down. An IP phone without internet isn't registered, and the PBX sends every call to the extension's "Unavailable" destination.

• Check whether the computers in the same office have internet.
• Meanwhile you can answer from an app on a mobile, connected over the cellular network.
• Worth preparing in advance: the "Unavailable" destination of the important extensions — to a mobile or to voicemail, so that no call gets lost.

About a backup internet connection and planning for outages — in backup internet and redundancy.

Only one side is heard, or the call drops after a few seconds

The call connected, but one side can't hear, or it disconnects after about 30 seconds. This is almost always a network problem and not the PBX: the router doesn't pass the audio correctly, or the internet provider blocks part of the traffic.

• Check whether it happens on all the phones in the office or only on one.
• Check whether it happens only behind a certain router — for example at home and not at the office.
• An extension has a periodic connection check setting, which helps the PBX keep in touch with a device behind a home router.

Background explanations — in NAT, router and latency and jitter. Choppy or "robotic" audio is usually a matter of connection quality and not of the settings.

Fax, alarm and special devices

Fax machines and alarms connect through a dedicated adapter, so they too need to be registered like any extension. A fax that doesn't go through or an alarm that doesn't dial the monitoring center — first check that the adapter is connected to power and to the network, and that its extension is registered.

A fax that arrives partial or cut off in the middle is usually a matter of connection quality. A more convenient option is to receive faxes by email and send a fax from a file — see virtual fax.

Error codes: what the number means

Telephony systems talk in numeric codes. If a phone, an app or a technician shows a code, here are the common ones:

The full list, with an explanation for each group of codes — in SIP codes.

After a change: a new router, an office move, an employee who left

Many problems start a day after a change that seems unrelated. If calls stopped working "suddenly", ask what changed this week:

• A new router or a new internet provider — phones that don't register, or one-way audio. Sometimes the new router's default settings interfere with calls.
• An office move — if an IP address restriction was set on the extension, a phone from the new address can't register until it's updated.
• A deleted extension — a queue, a group or a menu key that pointed to it is left without a destination.
• A new SIP password — a device that hasn't been updated keeps working until its next registration, and then stops.
• A change in a time group — affects every number and code that uses it, not only the one you changed.

So after every change in routing or equipment, it's worth making one test call in and one out — the same day, rather than waiting for a customer to call and complain.

A five-minute checking routine

When something doesn't work, go through a fixed order, from simple to complex:

1. A test call. Call yourself, from a mobile that isn't the office's, and note the exact time and what you heard.
2. Call history. Find the call on the "Call history" screen by the number. The status and the path say where it ended: "Not answered" — it rang and nobody answered; "Ended in a menu" — the caller didn't get past the menu; "Ended in the system" — a recorded message, a routing code or a disconnect right at the start.
3. Call route. On the number card — where the call is supposed to go at this hour.
4. The extension. In the extension editor, in the "Devices registered on the line" part — whether a device is connected, and whether failed registration attempts were recorded (almost always a wrong password).
5. Filtering. If you have the call filtering service — the "Blocked calls" card.

In most cases one of the five steps reveals the cause. Didn't find it? That's the time to contact us.

What to send us when you contact us

A request with the right details gets solved much faster:

• The exact time of the test call.
• Which number you called from, and which number you called.
• What you heard — ringing with no answer, busy, silence, a message (and what it said).
• A link to the call from the call history, if you found it — so we see exactly the same call.

You can send the request from the dashboard, with the "Report a problem" button — it attaches a screenshot of the screen you are on by itself.