Calls from (023) 9399 XXXX — Southampton & Portsmouth
Block (023) 9399 XXXX is allocated by Ofcom to Nationwide Telephone Assistance Ltd, on the Southampton & Portsmouth exchange (allocated 2007).
(023) 9399 XXXX is a number block in Southampton & Portsmouth, in the historic county of Hampshire, an area with a population of approximately 850,000. Standard landlines in this area use the format 023 9399 1234, with the first part being the dialling code and the rest being the local number.
This block — (023) 9399 XXXX — was allocated by Ofcom to Nationwide Telephone Assistance Ltd in 2007. Nationwide Telephone Assistance Ltd either operates the numbers directly or sub-allocates them to resellers and downstream carriers, which is why a single (023) 9399 XXXX prefix can be used by many different organisations. You can verify any allocation against Ofcom's National Telephone Numbering Plan, which is updated weekly.
The HMRC-impersonation scam continues to be the most-reported telephone scam in the UK, and blocks like (023) 9399 XXXX are sometimes spoofed for these calls. HMRC will never threaten arrest, demand payment by gift card or cryptocurrency, or use a 'press 1 to speak to an officer' menu. If in doubt, hang up and contact HMRC on the number printed on their gov.uk page.
If a (023) 9399 XXXX 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 (023) 9399 XXXX
Is (023) 9399 XXXX a real UK phone number?
Yes. (023) 9399 XXXX 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 Nationwide Telephone Assistance Ltd for use on the UK public telephone network.
Who owns the (023) 9399 XXXX number block?
(023) 9399 XXXX is currently allocated to Nationwide Telephone Assistance Ltd 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 (023) 9399 XXXX number based?
(023) 9399 XXXX is associated with Southampton & Portsmouth. UK geographic numbers historically indicated the location of the line, although VoIP services and number-portability rules mean a (023) 9399 XXXX 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 (023) 9399 XXXX?
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 (023)
Try a different block within the same UK area code:
