Are 0343 numbers free to call on O2?

You can use any inclusive minutes on your O2 tariff to phone an 0343 number for no charge, however if you have run out of minutes you will have to pay fees to connect the call.

0343 numbers are used by companies and organisations throughout the UK as a replacement for the more expensive 0843 set which are now illegal to be used as anything other than sales hotlines. O2 mobile customers can expect to pay a per-call access fee alongside a per-minute rate

Minimum cost of calling 0343 numbers from an O2 phone