Ten years ago, if you wanted two UK numbers on one iPhone or Samsung, your only option was downloading a virtual number app like Vyke, Swytch, Devyce, CircleLoop, or Hushed. Phones only had one physical SIM slot, so routing calls over the internet inside an app was a clever workaround.
Every iPhone sold since 2018 (iPhone XS and newer) and almost every modern Samsung Galaxy and Google Pixel has a built-in dual-SIM chip. Instead of running a buggy VoIP calling app over mobile data, you can download a SecondSim UK eSIM straight onto your handset's hardware. The difference in day-to-day reliability is night and day.
Why VoIP Calling Apps Frustrate UK Users
Virtual number apps (Vyke, Swytch, Devyce, Hushed) do not connect to mobile masts directly. They rent internet SIP numbers and push calls and texts through their own smartphone app over Wi-Fi or 4G data. Anyone who has used one for work knows the three things that go wrong:
- The app goes to sleep in the background: Both iOS and Android aggressively freeze background apps to save battery. When the VoIP app's background connection drops, a customer rings your business number and your phone never even lights up – you just get a missed-call notification twenty minutes later.
- Calls break up on the road: Because VoIP calls travel over mobile internet packets rather than prioritised GSM/VoLTE voice channels, driving down an A-road or standing in a customer's kitchen with one bar of 4G turns your voice into a robotic mess.
- You are stuck dialling inside a separate app: Want to call a client back from Apple CarPlay, Android Auto, or your recent calls list? With a VoIP app, your second number is walled off inside their app interface.
SecondSim is a real UK mobile eSIM on the Vodafone UK network. Once you tap the 1-click install link in your confirmation email, your second 07 number lives inside your phone's normal Phone and Messages apps. No extra app to keep open, no top-up credits to watch.
UK Second Number Comparison (2026)
| Criteria | SecondSim (Vodafone eSIM) | Vyke / Hushed | Swytch / Devyce |
|---|---|---|---|
| How It Works | Native Dual-SIM eSIM (Vodafone UK) | Internet VoIP app | Internet VoIP app |
| WhatsApp Business | ✓ Passes first time (7-day guarantee) | ✗ Routinely blocked as VoIP | Hit-and-miss (depends on block) |
| UK Bank, HMRC & Stripe 2FA | ✓ Full Vodafone MNO HLR support | ✗ Blocked by bank security filters | ✗ Often rejected for financial OTPs |
| Works Without Wi-Fi / Data | ✓ Yes (Standard mobile signal) | ✗ No (Needs live internet) | ✗ No (Needs live internet) |
| Price (Unlimited UK Calls/SMS) | £5.99/mo (£5.00/mo yearly) | Line fee + per-min/SMS credit bundles | £12–£20+/mo (+ VAT) |
Why WhatsApp Business and UK Banks Reject Virtual Number Apps
Over 60% of our UK customers get a second number either to run WhatsApp Business alongside their personal WhatsApp, or to pass two-factor authentication with UK banks (Monzo, Barclays, Revolut, Starling, Tide) and Stripe. We cover the network mechanics in detail in our eSIM vs VoIP guide.
In short: virtual number apps recycle numbers from non-geographic VoIP ranges. When you type a VoIP number into WhatsApp Business or a UK banking app, their Home Location Register (HLR) lookup sees that the number isn't attached to a physical SIM/eSIM network and rejects it with "This phone number is not a valid mobile number." Because SecondSim allocates real UK 07 numbers on Vodafone UK's mobile network, verification goes through first time.
Install a real Vodafone UK eSIM in 60 seconds
Uses your phone's native dialler & Messages app · Unlimited UK calls & SMS · 7-day WhatsApp & bank verification guarantee.