Calls from 01923 378 XXX — Watford
Block 01923 378 XXX is allocated by Ofcom to Colt Technology, on the Watford exchange (allocated 2006).
01923 378 XXX is a number block in Watford, in the historic county of Hertfordshire, an area with a population of approximately 96,768. Standard landlines in this area use the format 01923 378123, with the first part being the dialling code and the rest being the local number.
This block — 01923 378 XXX — was allocated by Ofcom to Colt Technology in 2006. Colt Technology either operates the numbers directly or sub-allocates them to resellers and downstream carriers, which is why a single 01923 378 XXX prefix can be used by many different organisations. You can verify any allocation against Ofcom's National Telephone Numbering Plan, which is updated weekly.
A common UK scam pattern uses blocks like 01923 378 XXX for 'tech support' calls: a caller claims to be from Microsoft, BT, or your antivirus provider, and tries to get you to install remote-access software. No legitimate UK tech-support team will phone you out of the blue and ask to take control of your computer.
If a 01923 378 XXX number called you and you're not sure who it was, the safest steps are: don't return the call until you've verified it (search the full number online first), don't share personal or financial details, and register the number with the Telephone Preference Service (TPS) if it's a marketing call. Persistent unwanted calls can be reported to Ofcom and the ICO. To block a specific number on most UK mobiles and landlines, you can also enable network-level call screening through your provider.
FAQs about 01923 378 XXX
Is 01923 378 XXX a real UK phone number?
Yes. 01923 378 XXX is part of an Ofcom-allocated UK number block — any number starting with that prefix is a real, dialable UK number assigned by Ofcom to Colt Technology for use on the UK public telephone network.
Who owns the 01923 378 XXX number block?
01923 378 XXX is currently allocated to Colt Technology in Ofcom's National Telephone Numbering Plan. The allocated carrier may operate the numbers directly or sub-allocate them to downstream resellers — both arrangements are normal under UK telecoms rules.
Where is a 01923 378 XXX number based?
01923 378 XXX is associated with Watford. UK geographic numbers historically indicated the location of the line, although VoIP services and number-portability rules mean a 01923 378 XXX number can technically be used anywhere a CP routes it. For most UK landlines the geographic match still holds.
How do I block calls from 01923 378 XXX?
On most UK smartphones, open the recent-calls list, tap the number, and choose 'Block this caller'. UK landlines from BT, Sky, TalkTalk and Virgin Media include free 'BT Call Protect'-style screening you can enable in your provider's app. You can also register your number with the Telephone Preference Service (TPS) at tpsonline.org.uk to opt out of legitimate UK marketing calls.
Other blocks in 01923
Try a different block within the same UK area code:
