Ofcom opens Vonage and Voxbone investigations over scam-misused phone numbers

25 September 2026. Ofcom has opened two separate investigations into cloud and VoIP providers Vonage Business Limited and Voxbone SA, over concerns that numbers allocated to them are being misused, including to perpetrate scams. The cases shift the fight upstream: instead of chasing fraudsters, the regulator is testing whether the firms that hand out numbers did enough to stop scammers getting them.

What the numbering rules expect from a provider

Ofcom allocates numbers — usually in large blocks — to telecoms firms, which can transfer them onward to other businesses and individuals. A provider must take appropriate steps to ensure its numbers are not misused by whoever it transferred them to, and are used in line with the National Telephone Numbering Plan. Ofcom's stated expectations: 'know your customer' due diligence on business customers before scammers reach valid numbers, keeping risk under review by monitoring for misuse, and responding proactively to incidents. Specifically, the probes will establish whether both companies met General Condition B1 — effective and efficient use of numbers, and the steps taken to oversee use. Both sit inside the enforcement programme into phone and text scams running since 2024; ISPreview expects outcomes no earlier than late spring 2027, with fines or mandatory process changes possible.

Why businesses that hold numbers should care

Numbers are the credibility layer of the phone system: callers answer numbers that look real — which is exactly why scammers chase them. When a range leaks into fraud, networks respond with blocking and caller ID withholding, and honest callers on the same range get caught in the crossfire. Ofcom has already tightened the network side of that fight (see our spoofed-calls explainer); these investigations target the supply side instead — and their checklist cascades to every business that holds numbers, including resellers.

Three checks to run this week

1. Inventory your numbers. List every number you hold, who allocates it, and what rings where. Numbers nobody can account for are liabilities — port or surrender them; our porting rules explainer covers your rights.
2. Make your caller ID genuinely yours. Calls originating on a number you own survive verification because they are real — DIDcomms' SIP phone and softphone presents your own business number on outbound calls from any device.
3. Check your provider's controls. KYC checks, monitoring and proactive response are now the explicit expectations — and if you resell via DIDcomms' wholesale DID programme, expect the same checklist to reach you.

The takeaway is simple: know your customer, monitor use, respond fast. If your numbers sit scattered across two providers, it is a good week to line them up on one number inventory you can account for.

Related: What is a DID number? · Spoofed UK mobile caller IDs withheld from 15 July 2027