Do-not-disturb and forwarding indicators usually show on the phone's display.
Start here: what exactly isn't ringing?
One phone never rings, but others do
Likely stage: 05, the extension. Do-not-disturb, forwarding or not being in the group. If it doesn't ring for internal calls either, check the handset, cable and port.
A whole team's phones stopped ringing
Likely stage: 03 or 04. A night mode switched on, or the number now routed to another group. Check the current mode first.
It only fails at certain times
Likely stage: 03. Automatic mode switching has the wrong times, or a mode was switched by hand and left on. See Time profiles and night service explained.
Calls ring the wrong phones
Likely stage: 02. The dialled number (the DDI) is routed to the wrong group, or the carrier now sends the number in a different format.
No calls arrive at all
Likely stage: 01. Check outgoing calls and your carrier first. See Escalate safely: when to stop and call an engineer.
How a call reaches a Mitel extension
| Stage | What happens | Usually called on Mitel systems |
|---|---|---|
| 01 Line | The call arrives on a SIP, ISDN or analogue line | Trunks, trunk groups |
| 02 Route | The dialled number is matched to a destination | DID or DDI routing |
| 03 Time | Day, night or holiday handling is chosen | Day/night modes, schedules |
| 04 Group | A set of extensions rings | Hunt groups, ring groups |
| 05 Extension | The person's own settings apply | DND, call forward |
| 06 Voicemail | Unanswered calls move on | Voice mail, auto attendant |
Names vary between Mitel platforms and releases.
Five checks, in order
- Test internally. Call the extension from another desk. If it rings, the phone works and the fault is in routing or groups. If not, check the display, cable and port, and try a known working phone in the same socket.
- Check the mode. Find out which mode the system is in now. Night mode during working hours explains a whole team going quiet. Ask who can switch modes by hand, and whether the automatic schedule changed.
- Check the routing. Note the exact number dialled, and find which group or extension it goes to in each mode. Wrong in day mode is the fault; different at night is normal.
- Check the group. Compare the hunt or ring group's members with who should ring. Also check how it rings: in a group that rings one phone at a time, phones low on the list may never get a turn. Hunt group types explained explains the patterns.
- Check the person's settings. Look for a DND or forward indicator on the handset and ask the person. A forward set for a day off and never cleared is very common.
Common causes at a glance
| What you see | Most likely cause | Check |
|---|---|---|
| Team silent since this morning | Night mode switched on by hand | 2 |
| Team silent every lunchtime | Mode schedule | 2 |
| New starter never rings | Not added to the group | 4 |
| One person never rings | DND or forwarding | 5 |
| Rings internally, not externally | Routing or group, not the phone | 3, then 4 |
Don't switch modes or edit groups to test a theory during working hours: other teams may share them. Get a configuration backup first.
every incoming line stops ringing, the group handles urgent calls, or nobody has admin access. See Escalate safely: when to stop and call an engineer.
If your system is out of support, this is a good moment to read Mitel MiVoice Office 250: support status. The same method on other systems: NEC SV9100 phone not ringing and Calls not reaching the right people.
What to try on a Mitel phone that won't ring
- If the lights flash but there's no sound, turn the ringer up with the volume keys while the phone is ringing. Mitel's guide also suggests resetting the phone to its defaults, or asking your administrator whether the feature is switched on. People report this fault on 5312 and 5330e phones, and not every thread found a cure, so if it follows the handset, try a known working one.
- If the person is in a hunt group, check they haven't been logged out of it. Someone logged out stops getting group calls. Log them back in, and restart the phone if that doesn't work.
- If it's a home or teleworker phone that misses some calls, test the home connection. The missed ring may be a network fault.
- To clear a forward on a MiVoice Office 250, 355 is the published code for forward all calls. Codes can be changed on your system, so check your own list. We couldn't confirm a single do-not-disturb code across systems.
Sources: Mitel 5320 user guide ↗ · Tek-Tips: flashes with no sound ↗ · Tek-Tips: teleworker missed rings ↗ · University of South Dakota: logged out of a hunt group ↗ · MiVoice Office 250 user guide ↗
Common questions
Why is my Mitel phone not ringing for external calls?
If internal calls ring it, the phone works: the external number is routed elsewhere, or a night mode or group setting is skipping it.
How do I tell if my Mitel system is in night mode?
Many systems show the mode on display phones or light a mode key. Your administrator can confirm the current mode.
Why does my Mitel phone go straight to voicemail?
DND or forwarding is usually set on the handset. Check the display for an indicator.
Why does a new starter's phone never ring?
They were probably never added to the hunt or ring group. Compare the group's members with the team list.
What's the difference between a Mitel hunt group and a ring group?
Broadly, a hunt group offers calls to members in a pattern, while a ring group rings members together. Exact behaviour varies by Mitel platform, so ask your maintainer how yours is set up.
What is the DND feature code on a Mitel phone?
It varies by system and setup, and many phones have a DND key or menu instead. Your user guide or maintainer can confirm the code for your system.
How do I forward calls on a Mitel 5212?
Use the phone's call forward feature, through its menu or a programmed key, and check for the indicator on the display. Steps vary by system, so follow the user guide for your setup.
Sources
Last checked 9 November 2026 against the sources listed here. Menus and defaults can differ by software release, so confirm them on your own system. Spotted a mistake? Tell us.
