VoIP

What Is Fixed-Mobile Convergence (FMC)? One Number on Every Device

Here’s a familiar picture for a small business. A customer rings the office number. The phone on the desk rings out because the person they need is working from home, out on a job or between sites. So the customer tries the mobile number they were given last time, which is someone’s personal phone. Next time they skip the office number altogether.

Multiply that across a team and you end up with customer relationships living on personal mobiles, calls nobody can track, and a business number that doesn’t do its job. Fixed-mobile convergence, or FMC, is the fix.

Fixed-mobile convergence in plain English

The name sounds technical, but it breaks down simply:

• Fixed – your business phone system, the one behind your office number
• Mobile – the smartphones your team carries
• Convergence – bringing the two together so they work as one

With FMC, a mobile phone becomes a proper extension of your business phone system, not just somewhere calls get forwarded to. It can transfer calls to colleagues, use the company voicemail and show your business number when calling out.

Why it matters for hybrid teams

Customers call one number and reach the right person

Whether someone is at their desk, at home or on the road, the call finds them. Customers don’t need to know where your team is working today, and they don’t need a list of mobile numbers.

Your numbers stay with your business

When staff give out personal mobile numbers, those customer contacts walk out of the door when the person leaves. With FMC, customers only ever have the business number. If someone moves on, their extension is simply reassigned.

Team features keep working away from the office

Transfer a call to a colleague, pick up from a ring group, or have calls recorded, all from a mobile. The office phone system comes with you instead of staying behind on a desk.

A consistent, professional first impression

Every outbound call shows the business caller ID. Customers see a number they recognise and can call back, rather than an unfamiliar personal mobile.

One device instead of two

Nobody wants to carry a work phone and a personal phone. On handsets that support two SIMs, a business eSIM can sit alongside a personal SIM, keeping business and personal numbers separate on one device.

Three ways to get your business number on a mobile

Not all “office number on your mobile” options are equal. Here is how the common approaches compare:

Apps are a good fit for laptops and for people who mainly work on Wi-Fi. For people who are genuinely out and about, having the extension built into the SIM removes the most common frustrations: apps that have logged out, patchy site Wi-Fi and battery drain.

How Edison FMC Mobile works

FMC Mobile is a mobile SIM, with eSIM available, that acts as your VoIP extension. It runs on the EE network and plugs into your Edison VoIP phone system.

• No app needed. Business calls come through the phone’s built-in dialler.
• No data plan needed for calls. Calls use the mobile voice network, not Wi-Fi or mobile data.
• One number, any device. Your extension can ring on your desk phone and mobile at the same time. Answer on whichever is nearest.
• Business caller ID. Outbound calls show your business number.
• Your phone system features. Transfers, voicemail, call recording and presence work as they do on the desk.

Setting it up is straightforward. We check your handsets are compatible, set up the extension, and send an eSIM QR code to scan. There is no hardware to install at your premises.

Who is FMC right for?

FMC tends to make the biggest difference for:

• Business owners who are rarely at one desk but can’t miss calls
• Trades and engineers on site all day who still need to be reachable on the office number
• Field sales teams who want customers to see a business number
• Healthcare and clinics, where practitioners move between rooms
• Multi-site businesses with managers moving between locations
• Hybrid teams splitting the week between home and office

If your whole team sits at desks all day, you may not need it. Desk phones and the gloCOM app could cover you perfectly well, and we’ll tell you so.

Things to check before you start

• Handset compatibility. Most recent smartphones support eSIM, but it’s worth confirming for each device. We’ll check this for you.
• Signal where your people work. Because calls use the EE mobile network, coverage at your office, at home and on regular sites matters.
• Company or personal phones. Decide whether the business eSIM goes on company-owned handsets or staff’s own phones, and agree a simple policy.
• Your phone system. FMC Mobile works with Edison VoIP, from £10 per extension per month. If you’re still on an old ISDN or analogue system, which is being switched off by January 2027, that’s the first thing to move.
• Mobile data. FMC Mobile handles business calls. If your team also needs business mobile plans for data, our unlimited SIM plans start at £16/month on O2, £23 on EE and £25 on Vodafone.

Bringing it all together

FMC works best as part of a joined-up setup: a VoIP phone system at the centre, reliable business broadband in the office, mobiles that act as extensions, and an AI Receptionist (£10/month plus 12.5p per minute handled) to pick up calls when nobody can.

Edison Networks has been providing business communications since 2013, and our Croydon-based team has over 30 years’ telecoms experience. We set it all up, look after it, and put it on one bill with one person to call.

Related: FMC Mobile | Business VoIP phone systems