01603 Area Code
The dialling code for Norwich: what 01603 numbers are, who holds them, and what to do about a call you don't recognise.
What Is the 01603 Area Code?
Norwich landline number. 01603 is the dialling code for Norwich. Numbers starting 01603 are landline numbers for that area. Internet phone services can use them too, so a caller is not necessarily in Norwich.
Who was the range allocated to?
Ofcom has allocated 01603 numbers to 90 providers. The largest holders are BT, Vodafone Ltd (C&W) and Virgin Media Limited.
Numbers can be moved (ported) between networks, so the network a caller uses today may not be the one Ofcom allocated the block to. The allocation does not identify the person or business using a number.
Had a call from a 01603 number you don't recognise?
We can't tell you who called: an area code only shows the type of number and the provider Ofcom allocated the range to.
- Don't call back in a hurry, even if a message says it's urgent. Never give bank details or security codes on a call you didn't expect.
- Block the number from your phone's recent calls list.
- Forward scam texts free to 7726. Report unwanted marketing calls to the ICO, and see Ofcom's advice on scam calls.
- Register your number with the Telephone Preference Service to opt out of sales calls.
About the 01603 Range
| Number type | Norwich landline number |
|---|---|
| Area | Norwich |
| Number format | 01603 XXXXXX |
| Allocated by Ofcom | 72% of the range, to 90 providers |
| First allocation on record | 15 July 1994 |
| Most recent allocation | 3 June 2026 |
Largest holders of 01603 numbers
| Provider (as allocated by Ofcom) | Share of range | First allocated |
|---|---|---|
| BT | 38% | 15 July 1994 |
| Vodafone Ltd (C&W) | 8% | 18 June 2013 |
| Virgin Media Limited | 5% | 27 January 1997 |
| Gamma Telecom Holdings Limited | 4% | 1 March 2004 |
| Sky UK Limited | 2% | 2 July 2013 |
| TalkTalk Communications Limited | 1% | 31 August 2011 |
84 more providers hold smaller blocks.
Allocation data: Ofcom numbering data, as published 28 October 2026.
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Common Questions About 01603 Numbers
Where is the 01603 area code?
01603 is the dialling code for Norwich. Numbers starting 01603 are landline numbers for that area. Internet phone services can use them too, so a caller is not necessarily in Norwich.
Is 01603 a mobile number?
No. 01603 is a landline (geographic) area code for Norwich. UK mobile numbers start with 07.
Who does the 01603 range belong to?
Ofcom has allocated 01603 numbers to 90 providers. The largest holders are BT, Vodafone Ltd (C&W) and Virgin Media Limited. Numbers can be moved (ported) between networks, so the network a caller uses today may not be the one Ofcom allocated the block to. The allocation does not identify the person or business using a number.
Who called me from a 01603 number?
We can't tell you who called. An area code only shows the type of number and which provider Ofcom allocated the range to. If you don't recognise a 01603 number, don't call back in a hurry, and never give out bank details or security codes on a call you didn't expect.
Block the number from your phone's recent calls list. Forward scam texts free to 7726, report unwanted marketing calls to the ICO, and see Ofcom's advice on scam calls.