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ONSIM vs Air Landline: which UK virtual landline is right for you?
This is one of the closest comparisons we publish. ONSIM and Air Landline both give you a UK landline number that rings on your mobile, with no broadband dependency. The differences are price structure, inclusive features and the upgrade path - ONSIM can move the number natively onto a SIM; Air Landline bundles more inbound extras into one flat plan.
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. Air Landline pricing checked July 2026 (£9.99/mo published on airlandline.com); verify live before deciding.
| ONSIM | Air Landline | |
|---|---|---|
| What it is | Virtual landline (divert) + SIM-native landline | Landline-to-mobile call forwarding service |
| Entry price | £5/mo + VAT (Virtual Landline) | £9.99/mo + VAT (all-inclusive) |
| Outbound calls show landline number | Yes - £10/user/mo Landline SIM (native) | Inbound-focused; check their site for outbound options |
| SIM-native option (number on SIM/eSIM) | Yes | No |
| Requires broadband | No | No |
| Call recording | Paid add-on (Landline SIM, on-network) | Included |
| Voicemail transcriptions | No | Included |
| Multi-mobile divert | Via hunt groups on Landline SIM (2+ users) | Included |
| Free trial | No (monthly rolling, cancel anytime) | 7 days |
| Analogue-phone replacement box | Yes (Landline Replacement) | No |
| Trading since | 2013 (SIM-native landline) | Company registered 2012 (Companies House 08003632) |
| Trustpilot | 4.6/5, 64 reviews | Reviewed on Trustpilot - check live rating |
When ONSIM is the better choice
- You want the cheapest credible entry point - £5/mo vs £9.99/mo
- You need outbound calls to display your landline number natively (Landline SIM, £10/user/mo)
- You want the number on a SIM/eSIM - no forwarding leg at all, calls ring like a normal mobile call
- You want one provider you can grow with: £5 divert → £10 SIM-native, without switching
- You have analogue phones, alarms or lifts to keep working after the 2027 PSTN switch-off (Landline Replacement)
When Air Landline is the better choice
- You want one flat all-inclusive price with call recording and voicemail transcriptions bundled in
- You'll use their inbound extras - welcome messages, working-hours rules, holiday voicemail, WhatsApp Business integration
- You want to try before you buy - 7-day free trial and a money-back guarantee
- You only need inbound forwarding and never plan to show the landline number on outbound calls
More about Air Landline at airlandline.com.
Frequently Asked Questions
Common questions before choosing between the two.
What's the main difference between ONSIM and Air Landline?
Both give you a UK landline number that rings on your mobile - they are genuinely close rivals. The structural difference is the upgrade path. Air Landline is a single all-inclusive call-forwarding plan at £9.99/month + VAT. ONSIM offers two tiers under one provider: a £5/month Virtual Landline (divert) and a £10/user/month Landline SIM where the landline number lives natively on a SIM - so inbound and outbound calls both use the landline number with no forwarding involved at all.
How does pricing compare?
ONSIM Virtual Landline is £5/month + VAT with up to 2,500 forwarding minutes. ONSIM Landline SIM is £10/user/month + VAT with unlimited UK calls and SMS (fair use). Air Landline's published price as of July 2026 is £9.99/month + VAT, all-inclusive, with a 7-day free trial and no contract. Verify Air Landline's live pricing at airlandline.com before deciding.
Is ONSIM a good Air Landline alternative?
If you like Air Landline's model but want a cheaper entry point (£5 vs £9.99) or the ability to make outbound calls that display your landline number natively, yes - ONSIM covers both from one account. If what you value is Air Landline's bundle of inclusive extras (call recording, voicemail transcriptions, WhatsApp Business integration) at a single flat price, Air Landline is a strong choice and switching may not gain you much.
Can I make outbound calls showing the landline number?
With ONSIM, yes - the £10/user/month Landline SIM puts the landline number on a SIM/eSIM, so every outbound call natively displays it. On the £5 divert plan, outbound calls still show your mobile number. Air Landline is primarily an inbound forwarding service; check airlandline.com for their current outbound options.
When is Air Landline the better choice?
Pick Air Landline if you want an all-inclusive inbound package at one flat price - their £9.99 plan bundles call recording, voicemail transcriptions, welcome messages, working-hours rules, multi-mobile divert and WhatsApp Business integration as standard, and it comes with a 7-day free trial and a money-back guarantee. For a pure inbound-forwarding buyer who will use those features, it's genuinely good value.
When is ONSIM the better choice?
Pick ONSIM if you want to start cheaper (£5/month), you need outbound calls to show your landline number (Landline SIM, £10/user/month), you want the number delivered natively on a SIM/eSIM rather than by divert, or you want a provider that also offers a plug-in Landline Replacement box for analogue phones ahead of the January 2027 PSTN switch-off. ONSIM has run SIM-native landline services since 2013.
Can I move my number between Air Landline and ONSIM?
Yes, in both directions - UK number portability is mandatory. ONSIM ports most UK landline numbers in within 10-14 working days. Porting into Landline SIM is included, into Virtual Landline it is a one-off £20+VAT, and ONSIM's port-out fee is £20+VAT. Air Landline also supports transferring numbers in and states you can take your number with you if you leave.
Do either of them need an app or broadband?
Neither service depends on broadband for call delivery - both route calls over the phone network to your mobile, which is a shared strength versus VoIP apps. ONSIM's Landline SIM goes a step further: the number lives on the SIM itself, so there is no forwarding leg at all and no app anywhere in the chain.