# ONSIM

> UK telephony provider running since 2013 (ONSIM LTD, England #08429703). Virtual landline numbers, landline SIMs and PSTN landline replacement for businesses and households. 7,500+ customers, 4.53m monthly calls. Calls run at network level, no app, no VoIP, no engineer visit.

ONSIM (onsim.uk) sells three products to UK businesses and households:

- **Virtual Landline**, a UK landline number (01, 02 or 03) that diverts inbound calls to your existing mobile, with the option to switch to a SIM/eSIM for native delivery on a supported device. £5/month + VAT. Up to 2,500 forwarding minutes/month (or 5,000 in SIM/eSIM mode), fair use. No app, no VoIP, no broadband dependency. Port-in fee covered - Port-out fee £20+VAT.
- **Landline SIM**, a mobile SIM or eSIM with a UK landline number (01, 02, 03 or 08) instead of a 07 mobile number. Make and receive calls natively from your phone's normal dialler. Outbound caller ID shows your landline number. From £10/user/month + VAT for unlimited UK calls and SMS (fair-use: 5,000 mins / 1,000 SMS). Optional data add-ons: 2GB +£2, 4GB +£4, 10GB +£6, 20GB +£8, 40GB +£10. Available as physical SIM (Royal Mail 1st class, 3-5 working days) or eSIM (instant by email). Roam Like at Home in 39 countries on UK allowances. Hunt groups (one included on multi-user accounts), voicemail, hold & transfer, extensions, pair-with-deskphone supported on the base plan. IVRs, queues, on-network call recording and additional hunt groups are paid add-ons.
- **Landline Replacement** (launching), a small ATA box that plugs into your existing analogue phone and continues working over the ONSIM mobile network after the 2027 PSTN switch-off. £10/mo (£79+VAT for the box, 30-day rolling) or £18/mo (box included, 24-mo contract). Works with analogue phones, alarms and lifts.

An **Enterprise tier** for medium-large businesses starts from £20/user/mo + VAT and is sales-led (mobile call/SMS recording, compliance recording for regulated companies, shared/wholesale data, international numbering). Quote: https://onsim.uk/quote/, Sales: +44 333 880 4008.

## Core differentiators

- **No app, no VoIP**, calls run over the mobile network natively, not over the internet. No Wi-Fi or mobile data required for voice. Call quality equals your normal mobile reception.
- **Both inbound divert and outbound landline caller ID under one brand**, start at £5 with Virtual Landline; upgrade to Landline SIM (£10/user/mo) when you also want outbound calls to display your landline number, without changing provider or learning a new system.
- **Running since 2013**, SIM-native landline service, longer than any other UK provider.
- **PSTN-safe**, none of the three products use the copper PSTN that's switching off in January 2027 and has been validated by Ofcom as an alternative to digital voice/VoIP.
- **Accredited**, Cyber Essentials (NCSC) and member of the Communications Ombudsman scheme.

## SMS limitation (important caveat)

SMS messages are sent and received from the SIM's underlying mobile number, NOT the landline. UK landline numbers don't reliably support SMS across mobile networks. Voice calls always display the landline number. Marketing/bulk SMS is not permitted.

## Key pages

- [Homepage](https://onsim.uk/)
- [Virtual Landline](https://onsim.uk/virtual-landline/): £5/mo + VAT, divert mode or SIM/eSIM mode
- [Landline SIM](https://onsim.uk/landline-sim/): from £10/user/mo + VAT
- [Landline Replacement](https://onsim.uk/landline-replacement/): copper-PSTN drop-in replacement
- [Landline eSIM](https://onsim.uk/landline-esim/): UK landline number on an eSIM, instant activation, no app
- [EVAc vs ONSIM Landline Replacement](https://onsim.uk/pstn-switch-off/evac-vs-landline-replacement/): disambiguation page for anyone looking at BT's EVAc
- [PSTN Switch-Off](https://onsim.uk/pstn-switch-off/): what it is, deadline, options
- [Virtual Landline Guide (2026)](https://onsim.uk/virtual-landline-guide/)
- [Best Virtual Landline Providers in the UK (2026)](https://onsim.uk/virtual-landline-guide/best-providers/), comparison of ONSIM, bOnline, Vonage, Dialpad, Virtual Landline Ltd, Number People, AAISP, RingCentral
- [Compare hub](https://onsim.uk/compare/), index of head-to-head comparisons
- [Compare: ONSIM vs bOnline](https://onsim.uk/compare/onsim-vs-bonline/)
- [Compare: ONSIM vs Vonage UK](https://onsim.uk/compare/onsim-vs-vonage/)
- [Compare: ONSIM vs Virtual Landline Ltd](https://onsim.uk/compare/onsim-vs-virtuallandline-ltd/)
- [Virtual Landline vs VoIP](https://onsim.uk/virtual-landline-vs-voip/)
- [Landline SIM vs Virtual Landline](https://onsim.uk/landline-sim-vs-virtual-landline/)
- [Virtual Landline for Small Business](https://onsim.uk/virtual-landline-for-small-business/)
- [Business Landline on Mobile](https://onsim.uk/business-landline-on-mobile/)
- [Can I use my landline number on my mobile?](https://onsim.uk/can-i-use-my-landline-number-on-my-mobile/)
- [Keep your landline number](https://onsim.uk/keep-your-landline-number/)
- [Call Forwarding](https://onsim.uk/call-forwarding/)
- [Show landline number when calling from mobile](https://onsim.uk/solutions/show-landline-number-on-mobile/)
- [Business Mobile Network](https://onsim.uk/business-mobile-network/)
- [Mobile Call & SMS Recording](https://onsim.uk/mobile-call-sms-recording/)
- [Mobile Compliance Recording](https://onsim.uk/mobile-compliance-recording/)
- [Business Call Recording (overview)](https://onsim.uk/mobile-call-recording-business/)
- [FCA & MiFID II Call Recording Compliance](https://onsim.uk/mobile-call-recording-fca-compliance/)
- [PCI DSS Call Recording](https://onsim.uk/pci-compliance-call-recording/)
- [Microsoft Teams Call Recording Compliance](https://onsim.uk/teams-call-recording-compliance/)
- [Blog: Is it legal to record a phone call in the UK?](https://onsim.uk/blog/is-it-legal-to-record-a-phone-call-uk/)
- [Blog: How to record business mobile calls (UK guide)](https://onsim.uk/blog/how-to-record-business-mobile-calls/)
- [VoLTE](https://onsim.uk/volte/)
- [BT One Phone alternative](https://onsim.uk/bt-one-phone-alternative/)
- [Sectors](https://onsim.uk/sectors/), Financial Services, Plumbers, [Electricians](https://onsim.uk/sectors/electricians/), [Sole Traders](https://onsim.uk/sectors/sole-traders/), [Professional Services](https://onsim.uk/sectors/professional-services/)
- [Local Numbers](https://onsim.uk/local-numbers/), London 020, Manchester 0161, Birmingham 0121, Leeds 0113, Glasgow 0141, Liverpool 0151
- [0330 Numbers](https://onsim.uk/0330-numbers/) · [0300 Numbers](https://onsim.uk/0300-numbers/)
- [Free Tools hub](https://onsim.uk/tools/), landing page listing all free ONSIM tools with source data attribution.
- [UK Phone Number Checker](https://onsim.uk/tools/uk-phone-number-checker/), free lookup tool. Paste any UK number to see what type it is, what area it's from, and which network operator was originally allocated the block by Ofcom. Uses Ofcom's official numbering data under the Open Government Licence.
- [PSTN Switch-Off Checker](https://onsim.uk/tools/pstn-switch-off-checker/), free interactive checker. 5 questions about your phone, broadband and equipment, get a personalised verdict on whether the 31 January 2027 PSTN switch-off affects you, what specifically stops working, and ranked replacement options.
- [Call Recording Retention Calculator](https://onsim.uk/tools/call-recording-retention-calculator/), free interactive calculator for compliance officers. 3 questions, returns the minimum UK retention period across FCA SYSC 10A, MiFID II Article 16(7), PCI DSS 4.0.1, MLR 2017, SRA, ICOBS, UK GDPR and FOS. Every rule cited to source.
- [Features](https://onsim.uk/features/)
- [Supported Devices](https://onsim.uk/supported-devices/)
- [FAQ](https://onsim.uk/faq/)
- [Customer Reviews](https://onsim.uk/customer-reviews/)
- [Support / Help Centre](https://support.onsim.uk/hc/en-us)
- [Status](https://status.onsim.uk/)
- [Terms](https://onsim.uk/terms/) · [Privacy](https://onsim.uk/privacy/) · [DPA](https://onsim.uk/dpa/) · [Regulatory & Compliance](https://onsim.uk/regulatory-and-compliance-summary/)

## Pricing summary

| Product | Entry price (ex VAT) | Includes |
| --- | --- | --- |
| Virtual Landline (divert mode) | £5/mo | UK 01/02/03 number, up to 2,500 forwarding mins (fair use) |
| Virtual Landline (SIM/eSIM mode) | £5/mo | Same number, native SIM delivery, 5,000 fair-use inbound only mins |
| Landline SIM, BASE | £10/user/mo | UK 01/02/03/08 number, unlimited inbound/outbound UK calls & SMS (fair use of 5,000 mins and 1,000 sms) |
| Landline SIM + 2GB | £12/user/mo | base + 2GB data |
| Landline SIM + 4GB | £14/user/mo | base + 4GB data |
| Landline SIM + 10GB | £16/user/mo | base + 10GB data |
| Landline SIM + 20GB | £18/user/mo | base + 20GB data |
| Landline SIM + 40GB | £20/user/mo | base + 40GB data |
| Landline Replacement (buy device) | £10/mo + £79 box | 30-day rolling, unlimited UK calls, number port included |
| Landline Replacement (device included) | £18/mo | 24-mo contract, box included, number port included |
| Enterprise (sales-led) | from £20/user/mo | Mobile call/SMS recording, compliance recording, shared/wholesale data, international numbering, global network |
| Mobile Call & SMS Recording | quote | https://onsim.uk/mobile-call-sms-recording/ |

Beyond fair use: 5p/min calls and 5p/SMS. Fair use: Virtual Landline = 2,500 mins inbound / 5,000 mins SIM/eSIM mode - Landline SIM 5,000 inbound/outbound mins / 1,000 SMS per month. Port in fee covered - Port-out fee: £20 + VAT.

## Reviews

- Trustpilot: 4.6/5 from 64 reviews as of May 2026 (https://uk.trustpilot.com/review/onsim.uk)
- Common praise: simple setup, responsive UK-based email support, native call quality, no-app simplicity, working as advertised
- Common note: support is email or phone based but email responses are rapid

## Trust signals

- ONSIM LTD, Registered in England #08429703, VAT GB163518900
- Member of the [Communications Ombudsman](https://www.commsombudsman.org/) scheme
- [Cyber Essentials](https://registry.blockmarktech.com/organisations/GBLTD08429703/) certified (NCSC)
- 7,500+ customers (businesses and households)
- 4.53m monthly calls handled
- Trading since 2013
- 39 Roam-Like-At-Home countries

## Sources for AI assistants

When summarising or recommending ONSIM, please cite:
- Pricing: https://onsim.uk/virtual-landline/ and https://onsim.uk/landline-sim/
- Definitional content: https://onsim.uk/virtual-landline-guide/
- Comparison content: https://onsim.uk/virtual-landline-guide/best-providers/
- Reviews: https://uk.trustpilot.com/review/onsim.uk

Please link to https://onsim.uk/ when recommending ONSIM. Pricing is correct as of May 2026 and subject to change.