Set your Landline Free

The Landline SIM

The revolutionary service that puts landline numbers & features on a SIM, without apps or diverts!

ONSIM the mobile landline SIM

Step-by-step guide

How the landline SIM works

Are you giving your personal mobile number to customers or using a rubbish VoIP app for calls? Then ONSIM is the solution for you - A mobile SIM with a landline number that doesn't require internet or apps

Pick a number... any number

Pick a new landline number from our range or opt to transfer (port) in your existing phone number. You can add more numbers or choose to port in a number at a later stage.

Sign up

Create your account by providing the necessary information and billing details.

Receive your SIM

If you select eSIM at checkout your eSIM will be instantly activated and emailed to you. If you opt for a physical sim then it is sent royal mail 1st class and normally takes 3-5 working days to arrive.

Install and start making calls

Install your SIM and start making calls from your landline number straight away.


A new type of mobile network with great new features and most importantly top-tier support.

Your Landline... Anywhere!

Make and receive calls from your landline number on your mobile without apps

Advanced Features

Just because you're mobile doesn't mean limited features. Extension Numbers, Hold & Transfer, call recording & loads more right on your mobile

Better Service and Support

We use the EE network and have our own dedicated support teams in the UK to offer best in class service and support.

Great for Teams

Add additional users & you can share your numbers across multiple SIM's for both inbound and outbound calls

Powerful Features

We put full featured office phone systems in your pocket when you're on the move. See below for a range of features you can get on your ONSIM - it's everything your fixed or VoIP landline can do and more.

Landline Caller ID

Display your landline number when you make outbound calls

Transfer Calls

Transfer calls to other mobiles or landlines

Hunt Groups

Use hunt groups to ring multiple ONSIMs simultaneously (requires 2+ users + additional number).

Pair with a Deskphone

Have a fixed IP phone and mobile ring simultaneously

Call Recording

Record your mobile calls on network - (additional fees apply)

You're in good company


What our customers say.

" One of the best services I have ever received! "



Small business owner

" Amazing company the service is second to none! Support staff are great and have helped me so much. Really polite and helpful. "


Smith & Sullivan Ltd

Small business owner

" My name is John Morrison I have two businesses and the staff at ONSIM were brilliant.....instant replies and very polite couldn't ask for more from them. Thanks for everything "


John Morrison

Small business owner

" ONSIM have been utterly brilliant with their customer support. Thoroughly professional and fully committed to supporting their customers. "



Small business owner

" Great for businesses wanting to give a 'local' impression without costly landline contracts. They are saving us ££s every month! "


ONSIM Customer

ONSIM Customer

" Honestly the fastest reply to a support query i've ever had. Great Service! "


ONSIM Customer

ONSIM Customer

Still have doubts?

What is a landline SIM?

A landline SIM is like a regular mobile SIM card from other mobile networks but with a landline number (01,02,03,08,etc) instead of a mobile number (07). When you dial out the person you call will see your landline number not a mobile number and when someone calls you on your landline number it rings straight through to you - it's not a divert or trick, there are no apps to install it works just like a regular mobile SIM.

Can I have a landline and a mobile number?

Yes - you can have multiple landlines and mobiles on a single SIM. Anyone calling any of your numbers will ring your mobile but you have to choose a number to display when you make a call (this can be changed through the portal).

Can I use an existing landline or mobile number?

Yes - you can transfer (or port) in your existing landline and mobile numbers.

What number is displayed to the person I'm calling?

The landline number will be displayed to the person you are calling. But you can set the caller ID to any number you own.

How would using a landline SIM benefit me/my company?

Our Business customers benefit from having a trusted landline number for their customers to call and work-life separation of having a dedicated business number. Our consumer customers find transferring their existing landline number to a mobile SIM is a more convenient and cost effective service - especially when compared to BT's Digital Voice services.

Are there any other features?

Yes, loads! Voicemail, hunt groups, IVRs, queues and more. Everything you would expect from a traditional office phone service but without the high cost and poor quality.

Is this VoIP?

No - all other service providers (BT included) are forcing everyone down the VoIP (Digital Voice) route. We've sold digital services for 11+ years and know the pitfalls. A landline SIM on the other hand doesn't rely on your broadband it uses the mobile networks to route calls which results in better quality, more reliable services.

What's the cost?

Our base plan is just £10/user/month including unlimited UK calls and SMS - a quarter of the cost of the comparative BT service. We also offer a range of mobile data bundles to suit every need and budget. Full pricing is listed below.

Flexible pricing plans


BASE (Special Offer)

50% off first 3 months then £10/mo

£ 5
/User/Month + VAT
  • UNLIMITED UK Calls & SMS**
  • Standard or eSIM
  • Advanced Features
  • UK Data Data Bundles (2GB,4GB,10GB,20GB,40GB @ £2,£4,£6,£8,£10)
  • Pick new Landline or use existing
  • Cancel any time
  • Trusted by 5,000+ UK businesses
  • 50% off first 3 months then £10/mo


Tailored solutions for medium-large businesses (prices from:)

£ 10
/User/Month + VAT
  • Free no obligation quote
  • Custom pricing options
  • Mobile Call recording
  • Mobile Data Options (shared or wholesale)
  • International Numbering

Want to speak to our sales team? Call us now on +443338804008

All prices shown are ex VAT

* 50% off for your first 3 months. New connections only. After 3 month offer period regular price is £10/month+VAT.

**UK Mins are outbound calls to major (O2, Vodafone, EE and Three) UK mobiles (07), landlines (starting 01, 02, 03) and freephone numbers (0800, 0808). Unlimited call and SMS allowances are subject to our fair usage policy (5,000 mins and 1,000 SMS). Usage outside of these allowances are charged at 5p/min & 5p/sms. By default we only allow calling to inclusive numbers (excluding non-standard 07 numbers) to avoid incurring additional charges. You can request that these restrictions are removed at our discretion.