by PBX.lu Editorial on October 15, 2026
How to stop giving customers your mobile number: a business number that rings your phone
Many small business owners in Luxembourg run their company from their personal mobile. At the start it is fast and costs nothing. Over time the number ends up on invoices, vans, websites and in hundreds of customer phones, and it never switches off. This article explains why that becomes a problem, who it affects most, and four ways to get a separate business number that still rings the phone in your pocket. It ends with providers active in Luxembourg that offer this.
This guide is for freelancers, tradespeople and teams of one to ten people. If you are choosing a full phone system for a small team, read our guide for a 5-person company as well.
🧭 On this page
The problem with sharing your mobile number · Who this affects · The solution · Four ways to set it up · What to check before you choose · Providers in Luxembourg that offer it
The problem with sharing your mobile number
Your personal number was not built for business. Once a customer has it, they keep it. They call at nine in the evening, send voice messages on Sunday, and expect an answer because they can see you are online. You cannot set office hours on a number that is also how your family reaches you.
Personal mobile number The number on your own SIM card. It belongs to you, not to your company. You cannot share it with a colleague, route it, or switch it off for business calls only.
🌙 No off switch. Work and private calls arrive on the same line, at any hour. Silencing the phone silences your family too.
🔁 No cover. When you are on holiday, ill or on another call, nobody else can answer. The caller reaches your private voicemail.
🚪 The number leaves with the person. When an employee uses their own mobile for clients, the clients follow them when they leave.
🔒 Customer data on a private phone. Contacts, call logs and messages sit next to family photos and private chats. Under GDPR, the business still answers for that customer data.
🏷️ Image. A mobile number on a website or invoice can look less established than a business number, especially to larger clients.
📍 Luxembourg context Since the law of 7 June 2023, the Labour Code (Article L.312-9) requires companies whose staff use digital tools for work to set rules on the right to disconnect outside working hours. If staff take customer calls on their private mobiles, those rules are hard to apply in practice.
Who this affects: five common cases
🔧 The tradesperson. A plumber or electrician has the number painted on the van. Calls come in during jobs, at dinner and at weekends. They want evening calls to go to voicemail, and they want to call customers back without showing their private number.
🏠 The real estate agent. Agents spend the day at viewings, so every missed call can be a lost lead. When an agent leaves, buyers and sellers should still reach the agency, not a former employee. See how this works in real estate.
💼 The freelance consultant. Clients are in Luxembourg, Belgium, France and Germany. A local business number and a professional caller ID matter, and so does a clear line between work time and private time.
🩺 The therapist or small practice. Patients should not have the practitioner's private number. Calls should come in only during consultation hours, with a clear message and voicemail outside them.
🛍️ The shop or restaurant owner. One number for bookings should ring the owner and one staff member at the same time. When staff change, the number and the booking history stay with the business.
The solution: one business number that rings your mobile
The fix is simple. You get a separate business number, often a Luxembourg number, or one in Belgium, Germany or France if you work across borders. Customers only ever see that number. Behind it, a phone system decides where each call goes: your mobile, a colleague, voicemail, or an opening-hours message.
Business number (DID) A phone number that belongs to your company account rather than to a SIM card. It can ring any device you choose, and you can move it to another provider later.
There is one test that matters most. When you call a customer back from your mobile, which number do they see? If they see the business number, your private number stays private for good. If they see your mobile, the problem comes back with the first return call.
🔑 The one rule Incoming and outgoing calls must both use the business number. Call forwarding on its own only solves the incoming half.
Four ways to set it up
📲 1. A second SIM or eSIM. Most phones now take two SIM cards. A second mobile line gives you a separate number on the same phone, and you call out from that line. Cost: a second mobile plan. Limits: it is still a mobile number tied to one phone. There is no cover from colleagues and no call routing, and office hours depend on you switching the line off.
↪️ 2. A business number with call forwarding. A fixed or virtual number passes every call on to your mobile. Incoming calls work well. Outgoing calls do not: when you call back from your mobile, the customer sees your private number. Each forwarded call also adds a second paid call, from the business line to your mobile.
📱 3. A Cloud PBX app on your phone. You install your provider's app. Calls to the business number ring the app over Wi-Fi or mobile data. Calls you make from the app show the business number. Office hours, voicemail and a colleague who rings at the same time are all set in one online dashboard. Cost: usually a per-user monthly fee. Limit: you need a data connection and reliable app notifications.
📶 4. A fixed-mobile convergence (FMC) SIM. A special SIM card links your phone to the phone system at network level. No app is needed, and calls use the mobile network, so quality does not depend on data. Outgoing calls show the business number. Limit: fewer providers offer it, usually only in some countries, and you need a SIM from that operator.
Mobile twinning A setting where your business extension and an existing mobile number ring at the same time. It is easy to set up, but calls travel over the normal mobile network, so the cost and the outgoing caller ID work like forwarding.
✅ Solves both halves: a Cloud PBX app or an FMC SIM. Customers see only the business number, in both directions.
⚠️ Solves part of it: a second SIM, plain forwarding or twinning. These are fine to start with, but check the outgoing caller ID and the cost per minute.
💶 What a forwarded call really costs
Every forwarded call has two parts: the customer's call to your business number, and a new call from your business line to your mobile. Your provider usually charges the second part per minute, at its rate for calls to mobiles. A busy line with long calls can end up costing more than an app subscription. With an app over data, that second call does not exist: the call reaches you over the internet.
🕘 Office hours and voicemail, set once
With an app or FMC, you set time rules in the dashboard. For example: Monday to Friday, 8:00 to 18:00, ring my mobile. Outside those hours, play a short message and take a voicemail that arrives by email. A holiday switch sends calls to a colleague instead. Our opening-hours message examples give ready-to-use wording.
🔐 What stays on your phone, and what does not
With an app, call history, voicemails and recordings sit in the business account, not in your phone's own call log. When an employee leaves, you remove their user and the number stays with the company. If they used their own phone, only the app needs to come off it. To keep your number when you change provider, see our number porting guide.
What to check before you choose
- Outgoing caller ID. Does a call from the mobile app show the business number every time?
- Cost per forwarded minute, if you use forwarding or twinning.
- Time rules and a holiday mode, without calling support.
- Voicemail to email, and who else can listen to it.
- Number countries. Can you get LU, BE, DE or FR numbers if you work across borders?
- Mobile contract. Does it work with any mobile operator, or only with that provider's SIM?
- Backup. What happens when the app has no data? Our business continuity guide covers this.
For how the features work in detail, see Fixed Mobile Convergence and the mobile app guide.
Providers in Luxembourg that offer it
Each provider below offers a way for a business number to ring a mobile. They differ in method, in price transparency, and in whether you need their own mobile contract. The facts come from the providers' websites and our provider profiles, checked in October 2026. Most providers do not say whether calls from their app show the business number, so ask before you sign.
⭐ Voxbi, Cloud PBX by Mixvoip
LUMethod: a mobile app for iOS and Android (plus Windows, macOS and browser), mobile twinning to any existing mobile number, and an FMC SIM in Luxembourg and Belgium through Mixvoip.
Caller ID: calls from the app or the FMC SIM show the business number.
Price: published. Voxbi Free covers up to three users and includes two numbers. Paid Voxbi One plans start at €1.20 per user a month, with numbers at €2.00 a month each, excluding VAT.
Numbers: 23 countries through Mixvoip, including LU, BE, DE and FR.
Mobile contract: any operator for the app and twinning. FMC needs a Mixvoip SIM.
🟠 Orange Luxembourg
LUThe Orange Cloud Phone app links an Orange professional smartphone to Orange Virtual PBX. The app can show the company number. Needs Orange mobile and a Virtual PBX subscription. Pricing on quote.
📶 Tango
LUThe Bizz2Go app works with Fix4Bizz cloud telephony over Tango's mobile network, so each user needs a Tango mobile subscription. Fix4Bizz costs €9.90 per user a month excluding VAT. Bizz2Go pricing is not published.
🏢 DEEP (POST)
LULuxZone lets the same extension ring a desk phone and a mobile, on CloudPBX and ConnectedOffice. The Webex and Teams apps also work as softphones. Mostly on quote. ConnectedOffice Essentials pricing is published.
🔗 Cegecom
LUManaged Com Business includes an iOS and Android app with mobile integration, call forwarding and presence. FMC needs Feature Package S or higher. Confirm with Cegecom whether the app makes full calls over data. Quote only.
📡 Telkea
LUThe UCall app on Net-PBX makes calls over data, falls back to the mobile network when data is weak, and has an FMC mode. Premium profile only. Quote only.
💬 Microsoft Teams Phone
GlobalThe Teams mobile app takes business calls over data, with any mobile operator. Teams Phone costs about €8 to €10 per user a month, on top of Microsoft 365 and a calling plan or operator connection.
⚠️ Ask every provider the same three questions. Does a call from the app show my business number? Do I need your mobile SIM? What does a forwarded minute cost?
📚 Want to see how this fits a full phone system? Explore the features guide or compare providers active in Luxembourg and the Greater Region.
📅 Ready to explore Cloud PBX for your business?
A short call can tell you which setup fits the way you work, whether that is an app, FMC or simple forwarding.