Mobile Phone systems for Law Firms & Solicitors
"MY SOLICITOR
NEVER TOLD ME THAT."
Half of legal work happens on the phone - advice given, instructions taken, undertakings discussed - and almost none of it leaves a record beyond the attendance note someone writes up afterwards. If they write it up.
ONSIM puts recorded numbers on every fee earner's mobile, natively ON-A-SIM - the firm's landline, each fee earner's existing mobile number ported in, or both side by side. Calls from court, from home, from the car are all captured, with optional network-level recording and transcription behind them, a complete log of every call answered or not, and one dashboard managing the lot.
Professional identity on every call, personal numbers kept private, and a contemporaneous record when it matters.
The file should include the phone calls
Tailored Phone Solutions for Law Firms
Key Features Built for Your Practice:
A firm phone system that lives on the mobiles your fee earners already carry. No apps, no VoIP dependency - the firm's number, a record of every call, and confidentiality taken as seriously as you take it.
The Firm's Number on Every Mobile
Fee earners make and receive calls on their own phones with the firm's landline number as caller ID - from chambers, court or the kitchen table. Clients see one professional identity, and personal mobiles stay out of client hands.
Recording as a Contemporaneous Record
On-network call recording (an optional paid add-on) captures client calls at network level - no apps, no buttons to press. When a client says they were never advised of a risk, the recording is a contemporaneous record of exactly what was said.
Transcripts as Attendance Notes
AI Insights (optional, opt-in add-on) transcribes recorded calls and makes them searchable - a draft attendance note for every call, and an answer to "what did we actually agree on the phone in March?" in seconds.
Call Logs That Feed Time Capture
Real-time logs show every call with duration, number and timestamp - including attempted calls that rang unanswered. Chasing a client who does not pick up is still work; on most networks it simply vanishes. Logs are available via API for your practice management system.
Confidential by Design
Recordings are encrypted, processed and stored in highly secure data centres, with BYO-archive support if you already have a retention platform. Recording and AI features are off by default and only run if you enable them.
Reception Without a Switchboard
Hunt groups ring the right people when the office number is called; hold, transfer and voicemail are included, and IVRs and queues are available as paid add-ons. A small firm sounds like a large one, without a phone system in a cupboard.
"The client says they were never advised."
Complaints and negligence claims against firms often come down to a phone call: the client says the risk was never explained, the fee earner is sure it was, and the file contains a three-line attendance note written up later that afternoon - or nothing at all. Courts and complaint handlers consistently give weight to contemporaneous records over recollection, and the SRA expects firms to keep adequate records of client matters. It does not mandate call recording - but a firm that has it rarely wishes it hadn't.
ONSIM records client calls at network level as an optional add-on - nothing installed on the handset, nothing a busy fee earner can forget to switch on. Recordings are encrypted, processed and stored in highly secure data centres, and we support BYO-archive so recordings can flow into the retention platform you already use. Add AI Insights (also optional and opt-in) and every recorded call has a searchable transcript - effectively an attendance note that wrote itself, filed at the moment the call ended.
The call logs matter too. ONSIM logs every call in real time with duration and timestamp - including attempted calls that rang and were never answered, which most mobile networks never record at all. Three attempts to reach a client before a deadline are work done and evidence of diligence; on ONSIM they exist on the record, and via our API they can land in your practice management system for time capture.
None of this is legal or regulatory advice, and no phone system makes a firm compliant by itself - how you record, notify and retain is for your COLP and your own advisers. What ONSIM provides is the record: what was said, when you called, and how long it took. Our call recording retention calculator covers the SRA and MLR retention rules commonly applied to firms.
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?
Can you record the mobile numbers our fee earners already use?
Yes. Fee earners can port their existing business mobile numbers to ONSIM - the same process as switching networks. Clients keep the number they already have, the handset experience is unchanged, and every call and SMS on that number is recorded at network level and managed centrally alongside the rest of the firm. Ported mobiles and firm landline identities run side by side on the same system.
Can fee earners call clients from their mobiles showing the firm's number?
Yes. With a Landline SIM, the firm's landline number is native on the SIM in each fee earner's phone - outbound calls display the firm's number and inbound calls to it ring the mobile directly. No app, no VoIP, no divert: it works like a normal mobile call because it is one.
Does the SRA require law firms to record calls?
No - and we won't tell you otherwise. The SRA expects firms to keep adequate records of client matters, but it does not mandate call recording. Firms choose to record because a recording is a contemporaneous record of advice given and instructions taken - far stronger in a complaint or claim than a note written up afterwards. Whether and how to record is your decision; this is not legal or regulatory advice.
How does call recording work, and can staff forget to turn it on?
Recording happens on the network, not the handset, so there is nothing to install and nothing to press - if recording is enabled for a user, their calls on the firm number are captured automatically. It is an optional paid add-on and is off by default. See mobile call & SMS recording for the full capability, including compliance-grade options.
Are recordings confidential and secure enough for privileged material?
Recordings are encrypted, processed and stored in highly secure data centres - large banks and financial institutions rely on the same ONSIM recording infrastructure for regulated calls. We also support BYO-archive: recordings can be delivered into the archive platform your firm already uses, so retention and access control stay under your policies. Support is UK-based if you ever need help. See compliance recording.
How long should we keep call recordings?
It depends on the matter type - SRA guidance points to six years as typical for client files, longer for wills and trusts, and MLR 2017 has its own five-year rules where they apply. Our free call recording retention calculator works through the common UK regimes with cited references. Treat it as a starting point for your compliance review, not a substitute for it.
Do we need to tell clients their calls are recorded?
If you enable recording you are responsible for using it lawfully. In practice UK firms typically notify - a line in the client care letter or terms of business, or an announcement on inbound calls. How you meet your obligations is one for your COLP or adviser; recording on ONSIM is opt-in and off by default.
Can call logs help with time recording?
Yes. Every call is logged in real time with the number, timestamp and duration - a factual backstop for time capture and a way to spot unbilled phone work. Uniquely, the logs also include attempted calls that rang unanswered: chasing a client who does not pick up is still work, and on most networks it leaves no trace at all. Logs are available in your dashboard and over our API for practice management integration. Read why other networks don't log attempted calls.
We are a small firm with no switchboard - how do inbound calls get handled?
A hunt group rings the right people when the office number is called - reception first, then fee earners, or everyone at once. Hold, transfer, extensions and voicemail are included on the base plan; IVR menus ("press 1 for conveyancing") and call queues are available as paid add-ons. One hunt group is included on accounts with 2+ users. You can also pair a deskphone so it rings alongside the mobile.
What are AI transcripts and are they suitable for the file?
AI Insights is an optional, opt-in paid add-on that transcribes recorded calls and makes them searchable in plain English - ask "when did we discuss the indemnity?" and find the call. Firms use transcripts as the raw material for attendance notes and for reviewing a matter before responding to a complaint. It only processes calls when you enable it; nothing is transcribed by default.
Can we keep the number the firm has used for decades?
Yes - port your existing landline number to ONSIM and keep your letterhead, website and directory listings unchanged. Porting typically completes in 10–14 working days and the port-in fee is covered. It also solves the January 2027 PSTN switch-off: your number moves to the mobile network rather than dying with the copper line.
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.