Setting up the 3CX mobile app
How to install and configure the 3CX app on iPhone or Android so staff can use their work number on mobile.
The 3CX mobile app turns any iPhone or Android into an extension of your office phone system. Staff make and take calls on their work number, see who is calling, transfer to a colleague and pick up voicemail, all without giving out a personal mobile number. For a tradesperson on site, a salesperson in the car or anyone working from home a few days a week, it is the difference between being reachable and being missed.
This guide walks through what the app does, how to get it set up correctly, and the handful of things that trip people up, so calls ring through cleanly and your battery does not pay for it.
What the 3CX mobile app actually does
The app is a softphone that registers as your 3CX extension, the same extension you use on the Web Client or the desktop app. Because it is the same extension, the experience is consistent everywhere you sign in.
Calls on your work number
outbound calls show your business caller ID, not the staff member's personal number.
Status and presence
set yourself Available, Away or Do Not Disturb so the system routes calls accordingly.
Transfers and conferencing
push a call to a colleague, a ring group or a queue without hanging up.
Voicemail and chat
listen to messages and use internal company chat.
One identity
answer on your desk phone in the morning and your mobile in the afternoon; it is the same number either way.
Before you install: the one thing that matters
Almost every mobile app problem comes down to one decision made when the extension was created, so get this right first.
Modern 3CX uses a push-based connection for the apps. Instead of keeping a constant link open and draining the battery, the system wakes the app through Apple and Google push services only when a call comes in. This is what makes the app practical for all-day use. For it to work, the extension must be enabled for the apps and the system must be reachable from the internet, usually via the built-in STUN handling or a Session Border Controller (SBC) on the office network.
You also need the welcome email 3CX generates for the extension. It contains a QR code that carries every setting the app needs. Scanning that QR code is the single easiest way to provision the app, and it avoids typing server addresses and credentials by hand. If you manage extensions yourself, see our guide on adding and managing extensions for where to resend that email.
Installing and configuring the app
The process is the same whether you are setting up one phone or twenty.
Install 3CX from the Apple App Store or the Google Play Store on each staff member's phone.
Open the welcome email on a computer or second screen so the QR code is visible.
In the app, choose to scan a QR code and point the camera at it. The app reads the server details, extension number and credentials automatically.
Grant the app permission to use the microphone, send notifications and, on Android, to run without being aggressively battery-managed (more on that below).
Place a quick test call out and have someone call the extension back to confirm two-way audio.
That is the whole job for most people. If a QR code is not available, the same details can be entered manually, but scanning is faster and removes typos.
Make sure calls actually ring
An installed app is not the same as a working app. A few phone-level settings decide whether the call ever reaches the screen.
Notifications must be allowed
push is how an incoming call wakes the app. If notifications are off, calls will not ring.
Battery optimisation (Android)
Android phones, especially Samsung, Xiaomi, Oppo and Huawei, will put background apps to sleep to save power. Exclude 3CX from battery optimisation or it may miss calls when the screen has been off for a while. This is the most common cause of "my mobile stopped ringing".
Do Not Disturb
check both the phone's system DND and your status inside the app; either one will hold calls back.
Use Wi-Fi or mobile data sensibly
the app needs a working data path. On patchy office Wi-Fi, letting it fall back to 4G/5G often gives cleaner audio.
If calls connect but the audio is one-way or drops out, that is usually a network or NAT issue rather than the app itself. Our guides on fixing one-way audio and NAT and troubleshooting call quality cover the fixes.
Battery, data and good habits
Because the app sits idle until push wakes it, day-to-day battery use is modest. A couple of habits keep it that way and keep staff happy.
- Set status deliberately. If someone finishes for the day, switching to Away or logging out stops after-hours calls reaching their personal handset.
- Pair the app with sensible business hours routing so calls go to voicemail or an after-hours destination instead of ringing a mobile at 9pm.
- For privacy, remind staff that outbound calls use the business number, so there is no need to hand out a personal one.
If you would rather not work through extensions, push settings and QR codes yourself, this is exactly the sort of setup we handle for clients every week. As a local Melbourne telco we can configure the apps across your team and check they ring properly before you rely on them. Give us a call on 1300 747 266 or get in touch through our contact page. You can read more about the platform on our 3CX phone system page, or look at a hosted PBX if you want the system in the cloud.
What we see installing this in Melbourne
The single biggest cause of "my mobile stopped ringing" callouts we get from Melbourne SMEs is Android battery optimisation, almost always on Samsung handsets bought outright by staff. Out of the box, Samsung's Device Care will quietly put 3CX to sleep after a few days of background life, and the fix is a 30-second toggle that no end user knows to look for. We walk through it on every handset during install and document it for the office manager.
The second pattern is patchy office Wi-Fi on the cheaper NBN plans. Plenty of Greensborough and northern-suburbs offices are on FTTN with 20Mbps upload at best, shared across a warehouse mesh, and the app sounds noticeably worse on Wi-Fi than on 4G. We test on the actual connection rather than on a phone sitting next to the router.
The other one is staff using the app on personal handsets and worrying their number is exposed. It is not, but the question comes up on every cutover, so we cover it in the handover training along with how to set status when finishing for the day.
Frequently asked questions
Will the 3CX app use my staff member's personal phone number?
No. The app makes and receives calls on the business extension and presents your company caller ID. The personal number stays private and is never shown to the people they call.
Why does my phone stop ringing after a while?
Almost always battery optimisation on Android putting the app to sleep, or notifications being switched off. Exclude 3CX from battery saving and confirm notifications are allowed. On both platforms, also check the phone's Do Not Disturb is off.
Does the app work over both Wi-Fi and mobile data?
Yes. It uses whatever data connection the phone has. On weak office Wi-Fi, allowing the phone to use 4G or 5G can give clearer calls. Either way the app needs a usable internet path to register and carry audio.
Can one person use the desk phone and the mobile app at the same time?
Yes. A single extension can be signed in on a desk phone, the desktop app and the mobile app together. Incoming calls can ring all of them, and you simply answer on whichever device suits you at the time.
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