UK dialling code · Essex
Chelmsford — 01245 dialling code
Calls from Chelmsford dial out on the 01245 UK area code (+44 1245). Below: who Ofcom has assigned each 01245 number range to, plus a reverse-lookup form for any specific 01245 caller.
About the 01245 dialling code in Chelmsford
01245 is the geographic UK area code anchored on Chelmsford, Essex, listed in Ofcom’s National Telephone Numbering Plan. The code reaches across the wider charging area surrounding Chelmsford rather than the town centre alone. When an inbound UK landline shows +44 1245 on Caller-ID, the originating exchange is most likely physically located in or near Chelmsford, with neighbouring exchanges on 01200, 01202, 01204.
Numbers in Chelmsford’s 01245 block were originally allocated to UK communications providers in 1,000-number sub-ranges (the legacy Ofcom block size for geographic codes), with newer allocations issued in 10,000-number blocks once the smaller blocks ran out. Each block is delegated to a Range Holder — typically Openreach (BT), Virgin Media O2, Sky, Gamma Telecom or one of a long tail of regional carriers — who is then responsible for assigning individual numbers to end-customers in the Chelmsford charging area. The full table further down this page shows every currently-allocated range on 01245 and the holder it was delegated to.
This is the same data Ofcom publishes every Wednesday in the public UK Numbering Data feed; we re-ingest the snapshot weekly, so the Chelmsford allocations you see here are at most seven days old. Because UK numbers are portable, the current carrier of any specific 01245 number in Chelmsford can differ from the Range Holder shown — see Range Holder vs current provider for the explanation. To identify a specific caller, paste the full number into the lookup above: you’ll get the Range Holder, the allocation status, the Chelmsford area-code metadata, and a live AI internet check summarising any public web reports about that exact number.
From abroad, a Chelmsford 01245 number is reached by dialling the international access prefix (00 from most of Europe, 011 from North America), then 44, then the local digits with the leading zero dropped. So a number written locally as 01245 123 4567 becomes +44 1245 123 4567 when dialled from outside the UK. Inbound calls to a Chelmsford landline are charged at the recipient’s standard call-receive rate (free in most consumer tariffs), and outbound calls from a UK mobile or landline to a 01245 number are billed at the caller’s own UK landline rate. Essex consumers and businesses with a 01245 CLI typically use Openreach copper or fibre, Virgin Media O2 cable, a Sky or TalkTalk retail bundle, or one of a long tail of regional or VoIP-based providers — the table further down this page shows the wholesale allocation that anchors each block, but the live retail carrier on a specific number can be different after porting.
If you have just received a missed call from a 01245 number and you don’t recognise it, the most reliable next step is to paste the full number into the lookup above before calling back. The Ofcom Range Holder data tells you which wholesale carrier the block was issued to, which often gives away whether the call is a local resident, a national business renting a Chelmsford-presenting CLI, or a VoIP service that could be operating from anywhere in the UK. The AI internet check then aggregates any public reports about the specific digits — Reddit threads, MoneySavingExpert forum posts, Trustpilot reviews, scam-reporting databases — so you have context before you decide whether to ring back.
Range holders allocated to 01245
No Range Holder data is currently loaded for 01245 (Chelmsford). Run the weekly Ofcom ingest to populate.
All allocated ranges on 01245
Showing up to 200 ranges serving Chelmsford, ordered by prefix.
No ranges loaded yet.
Nearby UK towns
Other dialling codes anchored on towns near Chelmsford or elsewhere in Essex.
Related lookups
- 01200 ClitheroeNearby UK area code
- 01202 BournemouthNearby UK area code
- 01204 BoltonNearby UK area code
- 0121 BirminghamNearby UK area code
- 01245 dialling code overviewCode-level summary for Chelmsford
- All UK towns A–Z594 dialling codes by town
- More Essex codesSame region
- All UK area codesBrowse every 01/02 dialling code
- Lookup any UK numberFree reverse phone lookup
- Caller-ID guideHow to identify an unknown UK caller
FAQs about 01245 in Chelmsford
What is the dialling code for Chelmsford?
Chelmsford uses the 01245 UK dialling code. In international format the same number is written +44 1245, dropping the leading zero. Calls originating from a landline in or near Chelmsford, Essex will typically present this prefix on Caller-ID.
Are calls from Chelmsford (01245) safe?
Most 01245 calls from Chelmsford are legitimate landlines belonging to local residents, businesses, or contact-centres operating from the area. Scammers can however spoof any UK area code, so a 01245 prefix on its own does not prove the caller is genuinely in Chelmsford. Paste the full number into the lookup above to see the Ofcom Range Holder for that block plus a live AI internet check that aggregates public web reports about the specific number.
What providers operate 01245 numbers in Chelmsford?
No Range Holder data is loaded yet for 01245. The most-allocated providers on this code are typically Openreach (BT), Virgin Media O2, and Sky Telecommunications Services, with smaller blocks held by Gamma Telecom, Vonage and a long tail of regional carriers. The full breakdown is in the table further down this page.
Where is the 01245 dialling code used outside Chelmsford?
01245 is the geographic dialling code anchored on Chelmsford, but the area covered by an Ofcom 01/02 code is broader than the principal town alone — it usually extends across surrounding suburbs and villages within the same charging area, all within Essex. Number portability also means a 01245 number can be used by a subscriber who has since moved elsewhere in the UK.
How do I dial a Chelmsford 01245 number from outside the UK?
Dial your country's international access prefix (00 from most of Europe, 011 from North America, 0011 from Australia), then 44, then the 01245 number with the leading zero dropped. So a Chelmsford number written locally as 01245 123 4567 becomes +44 1245 123 4567 in international format. The leading zero is a UK-internal national-significant prefix and is always replaced by +44 when calling from abroad.
Why might a 01245 number actually be calling from outside Chelmsford?
Three reasons. First, Ofcom number portability: a customer can keep their 01245 number after moving anywhere in the UK, so the registered subscriber may not be in Chelmsford any more. Second, business CLIs: a national call-centre can present a 01245 number on outbound calls to look local. Third, VoIP services often issue geographic numbers regardless of where the underlying subscriber actually lives. The fastest way to confirm origin is to use the lookup above and read the AI internet check — public reports often surface the actual caller even when the registered 01245 block doesn't match.