UK phone prefixes to watch (and which to leave alone)

Premium-rate and higher-cost prefixes

Numbers starting 09 (such as 090, 091, 098) are premium rate and can cost up to around £3.60 per minute plus an access charge, the highest-risk callback range.

Numbers starting 084 and 087 carry a service charge on top of your normal call rate. The 118 directory-enquiry numbers can be surprisingly expensive too. Be cautious about ringing any of these back unprompted.

The sneaky one: 070 personal numbers

A 070 number looks like a mobile (07...) but it is not. It is a 'personal number' that forwards calls elsewhere, and calling it can cost far more than a normal mobile call. It is a favourite disguise for nuisance and scam callers because it mimics a mobile.

If you get a missed call from a 070 number you don't recognise, treat it like a wangiri risk and don't ring back.

Free numbers you should NOT block

Numbers starting 0800 and 0808 are freephone, they cost you nothing to call, and many are legitimate banks, helplines and customer-service lines. Don't blanket-block these.

Standard UK geographic numbers (01 and 02) and ordinary mobiles (071 to 075, 077 to 079) are charged at your normal rate. The aim is to filter the genuinely risky ranges, not everything unfamiliar. Allociao is built around that distinction, flagging premium-rate and suspicious numbers while leaving legitimate freephone and contact calls to ring through normally.

FAQ

Is 070 a mobile number?

No. Despite starting 07, it is a personal forwarding number that can cost much more than a mobile call. Be cautious.

Are 0800 numbers safe?

Calling an 0800/0808 freephone number is free and many are legitimate. The number being free doesn't guarantee the caller is honest, but don't block these by default.

Which prefix is most expensive to call?

09 premium-rate numbers top the list, up to around £3.60 a minute plus an access charge.