Search for a list of UK mobile prefixes and you will find a dozen tables that confidently tell you which network owns which range. Read three of them and you will notice something awkward: they contradict each other. One says 071 and 072 belong to O2. Another gives 077, 078 and 079 to EE. A third splits the same ranges differently again.
None of them is lying. They are all describing something that stopped being true the moment number portability arrived — and the confusion has real consequences if you are buying a number, screening a call, or trying to work out why a call to a normal-looking mobile cost more than you expected. This guide explains what the digits genuinely tell you, what they cannot tell you, and which 07 ranges are not mobile numbers at all.
The short version: 071, 072, 073, 074, 075, 077, 078 and 079 are mobile ranges, plus the odd one out, 07624. 070 is personal numbering and 076 is pagers — neither is a mobile. And no prefix reliably tells you which network a number is on today.
How a UK mobile number is built
Every UK mobile number is eleven digits and begins 07. After that comes a four or five digit block that identifies the operator the number was first issued to, and the remaining digits identify the individual subscriber.
Written internationally, the leading zero is replaced by the country code: 07700 900123 becomes +44 7700 900123. The zero is a domestic trunk prefix rather than part of the number itself, which is why leaving it in when dialling from abroad causes the call to fail. If you store numbers for a business, storing them in the +44 form saves a great deal of trouble later.
Which 07 ranges are actually mobile
This is the part most guides get half right. The 07 space is not exclusively mobile, and the exceptions matter more than the rule.
| Range | What it is | Mobile? |
|---|---|---|
| 071 – 075 | Mobile phones, UK and Crown Dependencies | Yes |
| 077 – 079 | Mobile phones, UK and Crown Dependencies | Yes |
| 07624 | Isle of Man mobile — an out-of-sequence allocation sitting inside the pager block | Yes |
| 070 | Personal numbering — forwards calls to whatever phone the holder chooses | No |
| 076 (other than 07624) | Pagers | No |
The 070 range is the one that catches people. An 070 number looks like a mobile at a glance, and it is routinely mistaken for one, but it is a redirection service: calls arrive at the number and are forwarded to whichever phone the holder has nominated. The holder can change that destination whenever they like, which is exactly what makes the range useful to people who would rather not give out a real number.
The 070 story, and why it has changed
For years 070 had a bad reputation, and it earned it. Because the range carried a revenue share, calls could cost up to around £1.10 a minute, and most callers had no idea. Ofcom found that of roughly 2.6 million calls made to 070 numbers in 2017, an estimated one in five was connected to fraud — typically scams that lured people into ringing an expensive number and kept them holding on it.
That changed on 1 October 2019, when Ofcom capped the wholesale rate for 070 at the same level as ordinary mobile calls. In practice an 070 call should now cost you no more than ringing a normal mobile, and many providers include the range in standard allowances.
Worth knowing if you read older advice: guides written before October 2019 still warn that 070 numbers are expensive. That warning is out of date. The cost problem was fixed; what remains is simply that an 070 number is not a mobile, and is not something you should be sold as one.
Why the prefix cannot tell you the network
Here is the heart of the confusion. Ofcom allocates blocks of numbers to communications providers, and the first five or six digits of a number are normally enough to show which company first issued it. That original allocation is public, stable, and what every prefix table is really describing.
But UK numbers are portable. When somebody moves from EE to O2, they keep their number. The digits do not change, so the number still sits inside an EE-allocated block while the calls are actually carried by O2. The entity Ofcom recorded as the range holder and the network genuinely serving the customer are now two different companies, and nothing in the number reveals the split.
Multiply that by two decades of switching and the prefix becomes a historical artefact. Ofcom does not publish a live feed of which network currently serves which number, so no free lookup can tell you either. Commercial services can query the routing databases directly, and that is the only reliable method.
This also explains the contradicting tables. Ranges have been reallocated, operators have merged and rebranded, and each table froze a different moment in that history. They are all accurate about the past and all unreliable about the present.
The Crown Dependency catch
Mobile numbers in Guernsey, Jersey and the Isle of Man use the same 07 format as the mainland and look identical in a contact list. They are not always priced identically. Calls from the UK to mobiles in the Crown Dependencies are frequently charged at a higher rate than calls within the UK, and they are often excluded from inclusive minutes.
For most people this is a curiosity. If you are shopping for gold and VIP mobile numbers for a business whose customers will be ringing it from the mainland, it is a genuine cost consideration — and one that no pattern in the digits will warn you about.
How to check a number properly
Four checks that actually work
- Confirm the range is mobile. It should begin 071–075, 077–079, or be an 07624 number. Anything else on 07 is not a mobile.
- Count the digits. Eleven in national format. Ten after the leading zero, or in +44 form.
- Do not infer the network. If you genuinely need the current carrier, use a paid lookup that queries routing data. Free prefix tables cannot answer this.
- Check where it is based. Ask whether the number is mainland UK or a Crown Dependency, because it affects what your callers pay.
If you need a number for a mockup, advert or training material, use Ofcom’s reserved drama range: 07700 900000 to 07700 900999. Those thousand numbers are permanently withheld from allocation, so they can never ring a real person. Making up a realistic-looking 07 number almost always lands on somebody’s actual phone.
What this means when you are buying a number
Prefix confusion costs money in the premium number market, in three specific ways.
The first is paying a premium for a prefix on network grounds. Since the prefix does not establish the current network, a surcharge justified that way is a surcharge for nothing. Judge the number on its digit pattern instead, which is also what decides what a mobile number is worth on resale.
The second is buying outside the mobile ranges without realising. An 070 number can be made to look like an attractive mobile in a listing. It is not one, it cannot be ported with a PAC code like one, and it will not behave like one for your customers.
The third is the Crown Dependency issue above — an easy thing to miss and an awkward one to explain to customers later.
If you want the fuller picture on what drives price once you have confirmed a number is genuinely mobile, our guide to premium mobile numbers in the UK covers the pattern families, the going rates and the porting process in detail.
The short answer
A UK mobile prefix is a record of where a number came from, not a description of where it lives now. It will tell you reliably whether you are looking at a mobile at all, which is genuinely useful and rules out the 070 and 076 ranges that trip people up. It will tell you nothing dependable about which network answers when you dial, and any table promising otherwise is describing a snapshot of the past.
Treat the first two or three digits as a validity check and stop there. Confirm the range is mobile, confirm the length, ask where the number is based, and ignore the folklore about which operator owns what. That is the whole of the practical knowledge, and it is considerably less than most prefix guides would have you believe you need.
Common questions
Is 070 a mobile number?
No. 070 is a personal numbering range that forwards calls to a phone the holder chooses. It looks like a mobile but cannot be used or ported as one. Since 1 October 2019 it costs no more to ring than an ordinary mobile.
Can I tell which network a number is on from the prefix?
No. The prefix shows which operator the number was first allocated to. Because numbers are portable, the current network may be completely different, and Ofcom publishes no live record of it.
Why is 07624 different?
07624 is an Isle of Man mobile range that sits inside the 076 pager block as an out-of-sequence allocation. It is a genuine mobile range, unlike the rest of 076.
How many digits is a UK mobile number?
Eleven in national format, beginning 07. Internationally the leading zero is dropped and replaced with +44, giving twelve characters after the plus sign.
Which numbers can I safely use in an advert or mockup?
Use 07700 900000 to 07700 900999. Ofcom permanently withholds this block from allocation so it can never reach a real subscriber.
Sources
- Ofcom — Telecoms numbering, on how number ranges are allocated to providers and consumer portability rights.
- Area-codes.org.uk — 07 numbers overview, on which 07 ranges are mobile, the 070 and 076 exceptions, the 07624 allocation and Crown Dependency call charges.
- ISPreview — Ofcom implements cost cap for 070 calls, on the 1 October 2019 price cap and the fraud figures behind it.
Last reviewed 25 August 2026. Number ranges and Ofcom rules change; we re-check this guide when they do.