Mobile Phone systems for Builders
THE QUOTE THAT RINGS WHILE YOUR
HANDS ARE FULL
You're up scaffolding, mixing muck or halfway through a first fix - and the phone in your pocket is someone wanting a quote. If it goes unanswered, they call the next builder on the list.
ONSIM gives builders a proper business landline number that rings on the mobile you already carry, all natively ON-A-SIM. No apps, no desk phone, no office needed.
Look established, share calls across your firm, and stop losing work to voicemail.
Built on solid foundations
Tailored Phone Solutions for Builders
Key Features Built for Your Business:
All the benefits of an office phone system without the office. With ONSIM you take business calls anywhere on site - no apps, no Wi-Fi, no call diverts to mess about with.
Landline Caller ID
Put a landline number on your van, boards and quotes - and take those calls on your mobile, on site. When you ring a client back, they see the business number, not your personal 07.
Hunt Groups for Small Firms
One business number ringing you, your business partner and whoever runs the office - at the same time or in turn. Whoever is free picks it up, and the enquiry never hits voicemail.
Look Established, Win Bigger Jobs
Extensions, main contractors and commercial clients expect a firm with a proper landline. A recognisable 01 or 02 number on your paperwork helps you compete for the bigger contracts, not just the day rates.
Smart Call Handling
On the tools until 4? Set diverts by working hours, send overflow to voicemail, or have calls answered while you finish the pour. You decide where every call lands.
What our customers say.
" One of the best services I have ever received! "
Mubasher
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
Still have doubts?
I'm on site all day - how do I actually answer a landline?
The landline number rings your mobile. With a Virtual Landline (£5/month + VAT), calls to your business number are forwarded to the mobile already in your pocket. With a Landline SIM (£10/user/month + VAT), the landline number lives natively on your SIM - calls ring like any normal mobile call, and when you dial out the client sees your landline number too.
What happens when my hands are full and I can't pick up?
You choose. Send the call to voicemail, divert it to your business partner or whoever runs your office, or set up a hunt group so the business number rings several phones at once - first to answer takes the job. On multi-user Landline SIM accounts, one hunt group is included.
Will a landline number really help me win bigger jobs?
A recognisable local 01 or 02 number on your van, boards and quotes reads as an established firm rather than one bloke and a mobile. For extensions, commercial work and main-contractor tenders, looking the part matters - and unlike a real office line, this one costs from £5 a month and travels with you. Browse area codes on our local numbers page.
Can two or three of us share the same business number?
Yes. With Landline SIM, each of you has a SIM in your own phone and the business number can ring all of you - simultaneously or in sequence. Everyone can also display the same company number when calling clients back, so the firm always looks joined up.
Can I keep the number that's already on my van and boards?
Yes - you can port your existing landline or mobile number to ONSIM, so nothing on your signage, website or old quotes needs reprinting. Porting typically takes 10–14 working days and the port-in fee is covered.
Do I need an app or Wi-Fi? Sites rarely have either.
No. ONSIM is not VoIP - calls run over the mobile network like any normal call. If your phone has signal on site, your business line works. Nothing to install, nothing to log into, no dependence on site broadband that doesn't exist yet.
What does it cost?
Two options: Virtual Landline from £5/month + VAT - inbound calls forwarded to your existing mobile, no SIM swap. Or Landline SIM from £10/user/month + VAT - unlimited UK calls and SMS with the landline number natively on your SIM, so outbound calls show it too. Both are monthly rolling - cancel any time.
What about mobile data for emails, drawings and job photos?
Landline SIM has UK data bundles from £2/month (2GB) up to £10/month (40GB), so you can pull up drawings, send job photos and reply to emails from site on the same SIM.
Flexible pricing plans
Virtual Landline
Start simple - inbound calls forwarded to your mobile
- Inbound calls forwarded to your mobile
- No SIM swap needed
- Pick new landline number or use existing
- Up to 2,500 forwarding minutes/month
- No app, no VoIP
- Cancel any time
Landline SIM
Inbound & outbound calls - your landline number on your SIM
- UNLIMITED UK Calls & SMS**
- Inbound & outbound calls show your landline number
- Standard or eSIM
- Advanced Features
- UK Data Bundles (2GB,4GB,10GB,20GB,40GB @ £2,£4,£6,£8,£10)
- Pick new landline or use existing
- Cancel any time
- Trusted by 7,500+ UK businesses
Want to speak to our sales team? Call us now on +443338804008
All prices shown are ex 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 sole discretion.