All 080 numbers are now free and will not appear on your bill.

Free of Charge Numbers. Dialling the numbers below will be free of charge for all O2 customers and will not appear on your O2 Bill
999 Emergency services
101 Emergency services (Europe & many others)
105 National Power Cut services
111 NHS 111 Service
112 Emergency services (Europe & many others)
123 The Speaking Clock
999 55 Emergency Services Silenced 
116000     Missing Children hotline
116006 Helpline for victims of crime
116111     Child helpline
116117     non-emergency medical on-call service
116123     Samaritans
080* Free Calls (all 080 free calls)
0800 1111 ChildLine
0800 555111 Crime stoppers
0800 884444 The Line - ChildLine for Children in Care
0808 8082008 Muslim Youth Helpline
0808 8084994 The Mix (Under 25 Helpline)
18000 NGTS Emergency
18001 + free number NGTS Free Number
85251-85259 Not for profit SMS Short Code helplines
85258 Young Minds Crisis Messenger
O2 Pay Monthly - Free of Charge 0845 Numbers
0845 230 6010 0845 330 0670 0845 600 3502 0845 604 4407
0845 330 0007 0845 330 0683 0845 600 3702 0845 741 7417
0845 330 0022 0845 330 0684 0845 601 0467  
0845 330 0030 0845 600 1169 0845 601 0628  
0845 330 0669 0845 600 3102 0845 602 0260  
O2 Pay Monthly - Free of Charge 0870 Numbers
0870 087 0168 0870 241 3758 0870 444 3308 0870 444 3070 0870 512 2221
0870 220 3295 0870 241 3769 0870 444 3310 0870 444 3333 0870 521 4000
0870 220 3303 0870 242 2801 0870 444 3029 0870 444 3400 0870 582 5825
0870 220 3310 0870 444 2959 0870 444 3032 0870 444 3499 0870 586 0860
0870 220 3318 0870 444 2968 0870 444 3033 0870 444 6468 0870 600 3009
0870 220 3319 0870 444 2970 0870 444 3034 0870 444 6472 0870 600 5102
0870 220 3325 0870 444 2973 0870 444 3040 0870 444 6475 0870 600 7102
0870 225 4302 0870 444 2991 0870 444 3042 0870 444 6486 0870 606 0782
0870 225 7879 0870 444 2995 0870 444 3047 0870 444 6492 0870 606 1508
0870 241 0202 0870 444 2997 0870 444 3049 0870 444 6494 0870 873 0643