05603 corporate & VoIP numbers
Ofcom’s numbering data lists 100 number ranges starting 05603, allocated to 12 providers. The largest holder is BT, with 20% of them. 055 numbers are used for corporate networks; 056 numbers are location-independent numbers often used by internet (VoIP) phone services.
Who were 05603 ranges given to?
Providers Ofcom allocated these number ranges to.
- Not allocated to a provider48 ranges
- BT20 ranges
- Magrathea Telecommunications Limited9 ranges
- Inet Telecoms Ltd (Voipfone)8 ranges
- Colt Technology Services6 ranges
- Orange Business Holdings UK Limited2 ranges
- Exa Networks Limited1 range
- Andrews & Arnold (Numbers) Ltd1 range
- Cloudcall Limited1 range
- Zen Internet Limited1 range
- Digital Mail Limited1 range
- Net-Work Internet Ltd1 range
+ 1 more
Range status
How Ofcom lists the ranges starting 05603.
Allocations by year
Explore by the next digit
Each block below starts 05603. Pick one to narrow it down.
What a 05603 number tells you
What it is
055 numbers are used for corporate networks; 056 numbers are location-independent numbers often used by internet (VoIP) phone services.
What it costs
Costs vary by provider – check your tariff.
Watch out for
Because they are not tied to a place, these numbers say little about where a caller really is.
05603 numbers: common questions
Who owns 05603 numbers?
Ofcom allocated the ranges starting 05603 to BT, Magrathea Telecommunications Limited, Inet Telecoms Ltd (Voipfone) and others. Numbers can be moved between providers, so this shows who the range was originally given to – not who is using a particular number today.
How do I call a 05603 number from abroad?
Replace the leading 0 with +44. For example, a number starting 05603 becomes +44 5603 followed by the rest of the number.
How much does it cost to call a 05603 number?
Costs vary by provider – check your tariff.
Is a call from a 05603 number a scam?
Because they are not tied to a place, these numbers say little about where a caller really is. Check the full number on Who’s Calling to see if it belongs to a verified business and what other people have reported.
Did a 05603 number call you?
Check the full number to see if it belongs to a verified UK business and what other people have reported.
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