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ONSIM vs SwitchboardFREE: which UK business number is right for you?
SwitchboardFREE is one of the UK's biggest virtual-number platforms - 95,000+ businesses, 40+ free features, no contracts. ONSIM plays a different game: fewer bundled features, but the landline number can live natively on a SIM so calls work like normal mobile calls with no app and no VoIP.
This page is a fair side-by-side. Pick the one that fits your business, not the louder marketing.
Side-by-side
All prices ex VAT. SwitchboardFREE plan pricing couldn't be verified in July 2026 (rendered in-app) - check their site live before deciding.
| ONSIM | SwitchboardFREE | |
|---|---|---|
| What it is | Virtual landline (divert) + SIM-native landline | Virtual numbers + VoIP feature platform |
| Delivery | Mobile network - SIM/eSIM or call divert | Cloud platform - divert, apps, VoIP |
| Entry price | £5/mo + VAT | Low-cost/free entry advertised - verify live |
| Bundled features | Focused: number, forwarding, voicemail; IVR/queues as paid add-ons | 40+ free features advertised (routing, greetings, menus) |
| SIM-native option (number on SIM/eSIM) | Yes - £10/user/mo Landline SIM | No |
| Requires app for full feature set | No | Yes (mobile/desktop apps) |
| Outbound calls show business number | Yes - natively from the phone's dialler | Yes - via their apps/VoIP |
| Call quality during broadband outage | Unaffected (mobile network) | Divert unaffected; VoIP features need internet |
| Contract | Monthly rolling, cancel anytime | No contracts |
| Customer base | 7,500+ businesses | 95,000+ businesses (advertised) |
| Trading since | 2013 (SIM-native landline) | Long-established UK platform |
| Trustpilot | 4.6/5, 64 reviews | Reviewed on Trustpilot - check live rating |
When ONSIM is the better choice
- You want a landline number that works like a normal mobile call - no app, no platform to learn
- You need outbound calls to display the landline number natively from your phone's own dialler (Landline SIM, £10/user/mo)
- Call quality must never depend on Wi-Fi, broadband or an app being awake
- You want a £5 divert tier and a £10 SIM-native tier under one provider
- You need analogue phones, alarms or lifts to survive the 2027 PSTN switch-off without broadband (Landline Replacement)
When SwitchboardFREE is the better choice
- You want the maximum number of call-handling features (routing, greetings, department menus) bundled free
- You want the lowest possible starting cost - they advertise a free/low-cost entry point; verify live
- You're happy managing calls through their apps and web control panel
- You want a very large, established platform - 95,000+ UK businesses use it
More about SwitchboardFREE at switchboardfree.co.uk.
Frequently Asked Questions
Common questions before choosing between the two.
What's the main difference between ONSIM and SwitchboardFREE?
SwitchboardFREE is a virtual number and VoIP platform - numbers, call routing, IVR-style menus, apps and a large bundle of call-management features (they advertise 40+ free features and 95,000+ businesses). ONSIM is a mobile-network operator model: a £5/month Virtual Landline divert, and a £10/user/month Landline SIM where the landline number lives natively on a SIM - no app, no VoIP, no broadband dependency.
How does pricing compare?
ONSIM is £5/month + VAT for Virtual Landline and £10/user/month + VAT for Landline SIM with unlimited UK calls and SMS (fair use). SwitchboardFREE's plan pricing wasn't visible to verify when we checked in July 2026 (their site renders pricing in-app) - they are known for a low-cost/free entry point and no contracts, but check switchboardfree.co.uk for live plan prices before deciding.
Does SwitchboardFREE really have a free tier?
SwitchboardFREE has historically offered a genuinely free entry point (the clue is in the name) alongside paid plans, typically with limits on number type and minutes. We couldn't verify the current free-plan terms as of July 2026, so check their site. If a £0 starting price with basic features is the priority, they deserve a serious look - ONSIM has no free tier; its entry point is £5/month.
When is SwitchboardFREE the better choice?
Pick SwitchboardFREE if you want the biggest feature bundle for the least money at the inbound end - they advertise 40+ free features including call routing, greetings and departmental menus, plus mobile apps, with no contracts and instant activation, and they serve 95,000+ UK businesses. If you want to experiment cheaply with professional call handling before spending much, they're a strong starting point.
When is ONSIM the better choice?
Pick ONSIM if you want calls to work like normal mobile calls rather than through an app or divert platform. The Landline SIM (£10/user/month) puts the landline number on a SIM/eSIM: inbound and outbound calls natively use the landline number, call quality never depends on Wi-Fi or app behaviour, and there is nothing to install. ONSIM has run this SIM-native model since 2013 - longer than any other UK provider.
Can outbound calls show the landline number on each?
Both can, differently. SwitchboardFREE supports outbound calling with your virtual number via their VoIP apps and services. ONSIM does it at network level: the SIM itself carries the landline number, so any call you dial from the phone's normal dialler displays it - no app needs to be open.
Can I port my number between SwitchboardFREE and ONSIM?
Yes, in both directions - UK number portability is mandatory. ONSIM ports most UK landline numbers in within 10-14 working days; the port-in fee is covered and the port-out fee is £20+VAT.
Which is safer for the PSTN switch-off?
Both are PSTN-safe - neither uses copper lines. The difference is dependency: SwitchboardFREE's VoIP features rely on internet connectivity; ONSIM runs over the mobile network, and also offers a plug-in Landline Replacement box so analogue phones, alarms and lifts keep working after January 2027 with no broadband at all.