Mobile call recording for the rail supply chain
THE COSS CALLS THE PERSON IN CHARGE.
IS THAT CALL RECORDED?
Since March 2026, Network Rail standard NR/L3/OPS/301 requires safety-critical mobile calls - the COSS to Person in Charge conversations that set up safe systems of work - to be recorded and auditable. That includes contractors, agency staff and site mobiles far outside GSM-R.
ONSIM records those calls at network level, natively ON-A-SIM. Port your workers' existing mobile numbers in and they are recorded - same number, same handset, nothing to install. Every call and SMS on the number is captured inside the network and available in your dashboard, with an API for your safety management system.
No apps to fail on site. Works on the phones crews already carry, including rugged site handsets - check yours on our supported devices list.
NR/L3/OPS/301 compliance on the phones you already carry
Recording Built for Trackside Reality
Key Features Built for Rail Contractors:
Recording that lives in the network, not on the handset. The COSS phones the PC from a lineside access point at 3am on whatever phone is charged - and the call is recorded, logged and retrievable either way.
Network-Level Recording, No Apps
Calls are recorded inside the mobile network, on the number - not by an app that a worker forgets to install, an OS update breaks, or the native dialler bypasses. If the call was made, it was recorded (recording is an optional paid add-on).
Port In Existing Mobile Numbers
Workers keep the 07 numbers their colleagues, signallers and site contacts already have saved. Port them to ONSIM and every call and SMS on them is recorded and managed in the same dashboard - no new numbers to circulate before a shift.
Works on the Phones You Carry
Standard SIM or eSIM in the phones your teams already use - modern smartphones and rugged site phones alike (see our supported devices list). A recorded number can also sit alongside a personal number on one phone via eSIM, keeping personal calls private.
Audit Trail for Every Call
Real-time logs of every call on the number - including attempted calls that rang unanswered, which most networks never record. When an investigator asks for a specific call between two named roles on a specific date, you retrieve it, not reconstruct it.
SMS Recorded Too
Safety-critical arrangements increasingly leak into text messages. ONSIM records SMS on the business number at network level alongside calls, so the whole conversation is evidenced, not just the spoken half.
API for Your Safety Systems
Pull recordings, call logs and attempted-call evidence into your own safety management or assurance systems over the ONSIM API - so audit preparation is an export, not a scramble.
Why these calls must now be recorded
RAIB investigations into track worker safety kept finding the same thing: near misses where the safe system of work was set up or varied in phone calls nobody could later reconstruct. The result was a recommendation to record the calls that safety depends on, and Network Rail's answer is the NR/L2/OPS/301 standard and its NR/L3/OPS/301 modules, in force since March 2026. The scope Network Rail has confirmed: mobile phone calls between the Controller of Site Safety (COSS) and the Person in Charge (PC). NR/L3/OPS/301/02 also replaces NR/L2/OPS/033, the older standard for recorded communications in possessions.
The people making those calls are very often not Network Rail staff. They are contractors and agency workers on ordinary mobiles - outside GSM-R, outside any control room recorder. That is the gap the standard closes, and it is exactly the kind of recording ONSIM has done since 2013: at network level, on the phones crews already carry, with the record kept whether or not anyone on site remembered to press anything. We've written a full explainer: NR/L3/OPS/301, the rail call recording mandate explained.
To be clear: no phone service makes you compliant by itself, ONSIM is not "Network Rail approved" (no such approval badge exists for this), and nothing here is legal or contractual advice. Which of your people and calls are in scope is a question for your Network Rail contact or principal contractor. What ONSIM provides is the recording, retention and audit capability those requirements describe - on the phones your teams already carry.
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Still have doubts?
Does NR/L3/OPS/301 apply to a small contractor like us?
If your people hold Controller of Site Safety (COSS) or Person in Charge (PC) roles on Network Rail managed infrastructure, the calls between those roles are the ones the standard requires to be recorded - regardless of whether you are a principal contractor or a two-person labour supplier. The precise scope in your case comes from your contracts, so confirm it with your Network Rail contact or principal contractor. This page is product information, not legal or contractual advice.
Can you record calls on the mobile numbers our workers already use?
Yes. Port their existing business mobile numbers to ONSIM - the same process as switching networks - and every call and SMS on those numbers is then recorded at network level and managed in one dashboard. Colleagues, signallers and site contacts keep calling the numbers they already have. Ported mobile numbers and landline identities run side by side on the same system.
Do we need special handsets or an app?
No app, ever - recording happens inside the mobile network, so there is nothing to install, nothing for a worker to remember on a 3am shift, and nothing an OS update can silently break. Handsets do need to be compatible with the ONSIM network: most modern smartphones are, along with rugged site models such as CrossCall and Spectralink. Check a specific phone on our supported devices list or with the eSIM compatibility checker.
What about workers who use their personal phones?
With eSIM, a recorded business number can sit alongside the personal number on the same handset. Business calls on the recorded number are captured at network level; personal calls on their own number are not touched. One phone in the pocket, and the safety-critical calls are on the recorded line.
How do we retrieve a call for an audit or investigation?
Recordings and call logs sit in your ONSIM dashboard in real time, searchable by number, date and time, with an API to pull evidence into your own safety management systems. Logs include attempted calls that rang unanswered - useful when the question is whether contact was tried, not just what was said.
Is SMS covered as well as voice?
Yes. ONSIM records SMS on the business number at network level alongside calls. If arrangements get made or varied by text, that half of the conversation is evidenced too. See mobile call & SMS recording.
Do we have to tell people calls are recorded?
If you enable recording you are responsible for using it lawfully - in practice UK businesses typically inform staff via policy and, where relevant, callers via an announcement or terms. For safety-critical rail communications, recorded lines are the established norm rather than the exception. For your specific obligations speak to your own adviser. Recording is off by default and only enabled if you opt in.
Does ONSIM make us NR/L3/OPS/301 compliant?
No supplier can honestly claim that. The standard covers procedures and role assessment as well as recording - recording is necessary, not sufficient, and there is no "Network Rail approved" badge for phone services. What ONSIM provides is the piece most contractors are missing: complete, network-level recording of the calls in scope, with retention and an audit trail. Read our full NR/L3/OPS/301 explainer.
What does it cost for a typical crew?
Most SMB recording customers pay £20/user/month + VAT all-in: SIM or eSIM, UK minutes and SMS, network-level call and SMS recording, secure archival, and search and replay in the dashboard, with number porting included. UK data bundles from £2, and AI transcription (AI Insights) is an optional add-on for searching recorded calls. Monthly rolling, cancel any time - so seasonal and project-based crews can scale up and down. Request a quote for your crew size.
Our office landline needs recording too - can you do both?
Yes. The same system carries landline numbers: your office number on a Landline SIM or as a Virtual Landline, recorded under the same account with the same dashboard. Port-in is included on Landline SIM and a one-off £20 + VAT on Virtual Landline.
Simple per-user pricing
Rail Call & SMS Recording
What most SMB recording customers pay - all-in
- SIM or eSIM per user
- UK minutes and SMS
- Inbound & outbound call recording at network level
- SMS recording (both directions)
- Real-time call logs incl. attempted calls
- Secure archival, retained per your policy
- Search & replay via the ONSIM dashboard, plus API access
- Number porting included
- UK-based support
- 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.