Mobile phone systems for letting agents
THE TENANT SAYS NO ONE EVER CALLED BACK.
YOUR PHONE SAYS OTHERWISE.
Lettings runs on the phone: repairs reported at 11pm, access arranged on a call, promises about the deposit that nobody wrote down. When a dispute lands, the question is always who said what, and when.
ONSIM puts the branch number on every property manager's mobile, natively ON-A-SIM. Out-of-hours calls route to the on-call manager or contractor, and every call is logged - answered, missed or attempted.
The numbers belong to the agency, so when a property manager moves on, the landlords stay with you.
Management is won and lost on who said what, and when.
Tailored Phone Solutions for Letting Agents
Key Features Built for Property Management:
A branch phone system that lives on the handsets your team already carries. No apps, no VoIP, no desk phones ringing in an empty office - the agency's numbers, on the team's SIMs, with routing and records behind them. This page is about the management side; for negotiators and sales, see ONSIM for estate agents.
The Branch Number on Every Mobile
Property managers call tenants, landlords and contractors from the branch number, on their own handsets, wherever they are. Tenants save one number for the agency, not six personal mobiles - and inbound calls hunt across the whole management team until someone answers.
Out-of-Hours Emergency Routing
A burst pipe does not wait for opening hours. Time-of-day routing sends the branch number to the desk by day and the on-call manager or emergency contractor by night, with failover to a second contact if the first does not pick up. Change the rota yourself in the dashboard.
Proof You Made the Call
Real-time call logs include attempted calls - outbound calls that rang unanswered. When a tenant says nobody called to arrange access, or a landlord says they were never told about the repair, you have a timestamped record. Most mobile networks cannot show you this at all.
A Record of Who Said What
Deposit deductions, rent conversations, complaint handling - the calls that resurface months later. On-network call and SMS recording (an optional paid add-on) captures them at network level, with nothing for busy property managers to remember to press.
Numbers That Belong to the Agency
When a property manager leaves, their number - the one every landlord in their portfolio has saved - is reassigned in minutes: to a successor's SIM, a hunt group of the team or an IVR menu, with incoming texts delivered to email, no SIM required. The portfolio stays with the agency.
Texts on the Business Number Too
Tenants report repairs by text. With ONSIM those SMS go to the business number, not a personal mobile - deliverable to email, and captured alongside calls when recording is enabled, so the message trail around a tenancy stays with the branch. One honest limit: picture messages (MMS) cannot currently be recorded in the UK, so ask tenants to email photos of the leak rather than text them.
"We were never told. Nobody ever rang us."
Every letting agent knows this dispute. The tenancy ends, the deposit deduction is challenged, and the adjudicator decides on paper: whoever can evidence what actually happened tends to win. The tenant says the damage was reported months ago and nobody acted; the landlord says the agent never told them; the agent remembers three phone calls that now exist nowhere. Sales disputes end at completion - management disputes can surface years into a tenancy, long after anyone remembers the call.
ONSIM gives lettings the evidence layer it has always lacked. Real-time call logs - including attempted calls that rang unanswered - prove you rang the tenant to arrange access, whether or not they picked up. Optional on-network call and SMS recording captures what was actually agreed about the repair, the rent and the deposit. Letting and managing agents must generally belong to a government-approved redress scheme, and both deposit adjudication and redress complaints are decided on the evidence each side can produce - though schemes and adjudicators set their own rules, so this is not legal or regulatory advice; how you record, retain and rely on evidence is for your own compliance advisers.
And because the numbers belong to the agency, the management book does too. When a property manager moves on, their number is reassigned in minutes - to a successor's SIM, a hunt group of the team or an IVR menu, with incoming texts delivered to email. Existing numbers, including mobile numbers landlords already have saved, can be ported in and managed the same way. Handling sales as well as lettings? The same setup covers the branch - see ONSIM for estate agents.
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?
Our property managers already use their own mobiles with tenants and landlords. What now?
Two routes, and most agencies use both. The team gets agency-owned numbers on a Landline SIM (physical or eSIM), so tenants and landlords only ever save numbers the agency controls. And numbers already in circulation - including existing mobile numbers - can be ported in: everyone keeps calling the number they have saved, while the agency gains the logs, routing and optional recording behind it.
What happens when a property manager leaves?
You reassign their number in the dashboard, typically within minutes - and it does not need a SIM waiting for it. Point calls at a successor's SIM or eSIM, a hunt group of the management team or an IVR menu, and have incoming text messages delivered to email while you recruit. The landlords in their portfolio keep ringing the same number, and it keeps ringing your agency - not their new employer.
How do out-of-hours emergencies get handled?
Time-of-day routing sends the branch number to the office by day and the on-call property manager or emergency contractor by night, with a different pattern for weekends and holidays. Failover on no answer passes the call to a second contact, so a tenant with water coming through the ceiling always reaches a human. You change the rota yourself in the dashboard.
A tenant claims we never called them back about a repair. Can we prove we did?
Yes. ONSIM's real-time call logs include attempted calls - outbound calls that rang unanswered - timestamped against the number dialled. When a tenant says nobody rang to arrange access, or a landlord says they were never consulted, the record exists whether or not the call connected. Read why other networks don't log attempted calls.
How does call recording help in deposit disputes and complaints?
Deposit adjudication and redress complaints are largely decided on the evidence each party can produce, and in lettings the key conversations - the reported repair, the agreed deduction, the notice given - often happened on the phone. On-network call and SMS recording (an optional paid add-on) captures those calls with nothing to press. Letting agents must generally belong to an approved redress scheme, and adjudicators and schemes set their own evidential rules - so this is not legal or regulatory advice; how you record, retain and rely on recordings is for your own compliance advisers.
Do we have to tell tenants and landlords that calls are recorded?
If you enable recording you are responsible for using it lawfully - in practice UK businesses typically inform callers, for example with a short announcement or a line in your terms of business. Recording is off by default and only enabled if you opt in. See mobile call & SMS recording.
What happens to our branch landline at the PSTN switch-off?
The UK's copper phone network is being switched off, and traditional branch landlines will stop working. ONSIM is PSTN-safe: port your branch number to ONSIM and it lives on the mobile network instead - on the team's SIMs, not a box in the back office. See our PSTN switch-off guide.
We have multiple branches - can each keep its own local number?
Yes. Each branch keeps or picks its own local number - see local numbers for every UK area code - with its own routing and hunt group, all under one account. A SIM can carry more than one number, so a property manager covering two branches displays whichever branch they are calling for.
We do sales as well as lettings. Does this cover both?
Yes - same account, same SIMs. This page covers the management side: repairs, tenants, landlords and disputes. The sales side - instructions, viewings, offers and negotiator numbers - has its own page at ONSIM for estate agents. A branch can run its sales and lettings numbers side by side, each with its own routing, on the same handsets.
What does it cost for a typical branch?
The Landline SIM is £10/user/month + VAT with unlimited UK calls and SMS under fair use, hunt group included on 2+ user accounts, and UK data bundles from £2. A Virtual Landline at £5/month + VAT suits a single advertised number forwarded to a mobile. Call and SMS recording is an optional paid add-on - most smaller agencies that take it pay £20/user/month + VAT all-in - and AI Insights transcription is a further opt-in add-on. Monthly rolling, cancel any time. Port-in is included on Landline SIM and a one-off £20 + VAT on Virtual Landline.
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
The branch number on every property manager's handset
- UNLIMITED UK Calls & SMS**
- Numbers owned by the agency, reassignable in minutes
- Hunt groups, failover and time-of-day routing
- Standard or eSIM
- UK Data Bundles (2GB,4GB,10GB,20GB,40GB @ £2,£4,£6,£8,£10)
- Pick new numbers or port 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.