Most small business owners end up handing out their personal mobile number at some point — on an invoice, a van sign, a business card printed in a hurry — and then spend years fielding work calls on the same line their mum uses to ask about Sunday lunch. It’s rarely a deliberate choice. It’s just what happens when getting a “proper” second line looks like a faff: a new contract, a new SIM, maybe a whole second handset for every member of staff.
It doesn’t have to be that involved. Between app-based numbers, UK business eSIMs, and dual-SIM support that’s now standard on most phones, there are several ways to give yourself — or your team — a second number without buying a second phone.
Why bother, if the personal number “works fine”
It usually works fine right up until it doesn’t. A few reasons this comes up for SMEs specifically:
- You don’t want your personal number on public-facing material — a website, invoices, a shop window — where anyone can save it, ring it out of hours, or pass it around.
- You’re taking on staff or contractors and want them reachable on a business number, without buying and managing a fleet of company handsets.
- You want calls answered consistently — with call routing, voicemail, or an auto-attendant — rather than however each person’s personal phone happens to be set up.
- Someone’s leaving the business and you need the number to stay, even though the person doesn’t.
- You’re testing a new venture, a seasonal line, or a second brand, and don’t want to commit to a full contract for it.
Roughly speaking, there are three ways to solve this, and they suit different situations.
Business phone apps: cheapest to start, best for small teams
These give you a number that runs through an app rather than a SIM — calls and texts route over data or Wi-Fi, and the app usually adds features a personal phone doesn’t have, like call routing, shared inboxes for a team, or voicemail-to-text.
CircleLoop, built in the UK, is worth starting with for that reason alone — support and billing are in sterling, not converted from a US price. It runs from £5/month + VAT per user on a pay-as-you-go basis (calls billed at 3p/minute) or £15/month + VAT per user unlimited, and includes a UK landline number, with mobile numbers available as an add-on from £2/month. Quo (formerly OpenPhone) and RingCentral cover similar ground with more built-in CRM and call-analytics features, generally starting somewhere around £8–£25/month per user depending on the tier.
One thing worth flagging if you’ve read about this online: a lot of the “best second number app” advice is written for a US audience. Google Voice, in particular, is a US-only product for business use — it isn’t a sensible option for a UK-based business, whatever the American blog posts say.
UK business eSIM services: a real mobile number, no new contract
If an app-based number feels a bit too “virtual” — and you want something that behaves exactly like a normal UK mobile number, with proper call quality and no need to open an app to use it — a business eSIM service is the middle ground. SecondSim is a UK example: staff get a genuine carrier-grade UK mobile number added to their existing phone via eSIM, activated by tapping a link, with no separate handset and no long-term contract. It’s priced from £5.99/month + VAT per seat, billed on one consolidated invoice, and numbers can be paused, reassigned, or ported out with a standard PAC code if someone leaves. For a team of ten, that’s a noticeably different cost profile to ten separate mobile contracts with handsets.
Or go straight to your network: dual SIM and business eSIM
All four major UK networks — EE, Vodafone, Three, and O2 — now offer business eSIM on current plans, and most modern phones (iPhone XS onwards, and the majority of recent Android handsets) support running two lines at once: a physical SIM plus an eSIM, or two eSIMs on newer iPhones. Both numbers can make and receive calls and texts simultaneously; the only real limitation is that the phone uses one line for data at a time, though it can be set to switch automatically.
This route means an actual second mobile contract rather than an app subscription, so it costs more than the options above, but it’s the one to reach for if you want full carrier call quality and a completely standard number — useful for a genuinely permanent business line rather than something you might reassign or cancel later. It’s also the simplest way to hand staff a second, remotely-issued number for BYOD: eSIM profiles can be assigned and deactivated without ever touching the device, which is one less thing to manage if someone’s working from home or leaves the business unexpectedly. At the cheap end, giffgaff’s eSIM is a low-commitment, pay-as-you-go way to add a second number to a phone without any contract at all, which suits a very small or seasonal use case.
Questions worth asking before you commit to any of them
- Is the number a real UK mobile number, or a VoIP number that some contacts’ phones may flag or fail to recognise?
- What happens to the number if a staff member leaves — can it be reassigned or ported without a gap in service?
- Is there a minimum contract term, or can you cancel or resize the number of seats month to month?
- Does the service work reliably on mobile data, or does it need Wi-Fi/strong signal to function properly?
- Where is call and message data stored, and does that matter for your GDPR obligations if you’re handling customer details over it?
The Gaffer’s take
The cost of running a second number is a legitimate business expense either way, so the real decision isn’t tax — it’s how permanent you need the number to be. If you’re testing something, or want the flexibility to add and remove numbers as the team changes, an app or a UK business eSIM service is the lower-commitment route and considerably cheaper than a stack of separate mobile contracts. If the number needs to be rock solid and behave exactly like a normal mobile line — no caveats, no app dependency — a proper second SIM from your existing network is worth the extra cost. Either way, the fix for “everyone’s got my personal mobile number” is cheaper and quicker to put right than most people assume.