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ONSIM vs bOnline: which UK landline solution is right for you?
Both are UK business phone providers - but they solve different problems. ONSIM delivers a landline number natively over the mobile network: no app, no VoIP, no broadband dependency. bOnline is a full cloud-VoIP phone system delivered via an app, with rich call-management features for teams.
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. bOnline pricing checked May–June 2026; verify live before deciding.
| ONSIM | bOnline | |
|---|---|---|
| Delivery | Mobile network - SIM/eSIM or call divert | VoIP / cloud PBX - app on phone or desk handset |
| Requires app | No | Yes (for mobile use) |
| Requires broadband | No | Yes |
| Entry price | £5/mo + VAT (Virtual Landline) | ~£7/user/mo + VAT (Starter) |
| With outbound landline CLI | £10/user/mo + VAT (Landline SIM) | ~£13/user/mo + VAT (Pro) |
| Number types | 01, 02, 03, 08 (650+ dial codes) | 01, 02, 03, 08 |
| Hunt groups / multi-user | Yes (one included on multi-user accounts) | Yes (rich call routing) |
| IVR menus, queues | Paid add-ons | Included on higher tiers |
| Call quality during broadband outage | Unaffected (mobile network) | Calls stop |
| PSTN switch-off-safe | Yes | Yes (uses broadband) |
| Trustpilot | 4.6/5, 64 reviews | 4.5/5, 15,000+ reviews |
When ONSIM is the better choice
- You want the simplest possible UK landline on a mobile, no app to install
- Your team is mobile-first - out on jobs, on the road, working remotely
- Call quality matters and you don't want to depend on Wi-Fi or app behaviour
- You're replacing a copper PSTN line ahead of January 2027 with no broadband (Landline Replacement)
- You need outbound calls to display your landline number natively (Landline SIM)
When bOnline is the better choice
- You need a full multi-user cloud PBX with extensions, call queues and IVR menus
- Your team is desk-based with reliable broadband
- You want CRM integrations, conference bridges, and analytics built in
- You're standardising on IP desk phones across an office
More about bOnline at bonline.com.
Frequently Asked Questions
Common questions before choosing between the two.
What's the main difference between ONSIM and bOnline?
ONSIM delivers a UK landline number natively over the mobile network - calls work like a normal mobile call with no app, no VoIP and no broadband dependency. bOnline is a cloud-VoIP phone system delivered via an app, with features like call queues, IVRs and CRM integrations. ONSIM suits mobile-first businesses that want simplicity; bOnline suits desk-based teams that want a fuller phone system.
How does pricing compare?
ONSIM Virtual Landline starts at £5/month + VAT. ONSIM Landline SIM is £10/user/month + VAT including unlimited UK calls and SMS. bOnline's entry-level plan starts at around £7/user/month, with higher tiers around £13/user/month for full VoIP feature sets. Verify bOnline pricing live before deciding - VoIP plans bundle differently.
Which has better reviews?
ONSIM has a 4.6/5 Trustpilot rating from 64 reviews. bOnline has a 4.5/5 rating from over 15,000 reviews. Both are strongly positive. The review-count difference reflects business model: bOnline is a much bigger residential+business VoIP operator while ONSIM is a focused B2B SIM-native provider.
When is ONSIM the better choice?
Pick ONSIM if you want the simplest possible UK landline experience on a mobile, you don't want to install an app or depend on broadband for call quality, you need outbound calls to display your landline number natively (Landline SIM), or you're replacing a copper PSTN line that's being switched off in 2027 and want a no-broadband route (Landline Replacement).
When is bOnline the better choice?
Pick bOnline if you need a full multi-user VoIP phone system with call queues, IVR menus, CRM integrations, conference bridges and desk phones. bOnline's strength is the cloud-PBX feature set for a team based at desks with reliable broadband.
Can I switch from bOnline to ONSIM (or vice versa)?
Yes. ONSIM can port most UK landline numbers - the process typically takes 10-14 working days. bOnline similarly supports number porting in both directions. ONSIM's port-in fee is covered; port-out fee is £20+VAT.