Hi @Anonymous and Welcome to the Comminity Forum,
Do you have Mobile data turned on ?
Settings > Mobile > Mobile data.
If you dont have a data allowance in your tariff beware you will be charged £1 per day for 50mb of usge which is called Web Daily.
You should then see the data connection type nest to the O2-UK logo in the search bar.
Is this a new contract ? if so it may take a little while to settle. Upto 24 hours typically.
Turning airplane mode on and off helps the connection.
Is this an upgrade and was you given a new sized sim card ? If so did you perform the sim swap. If not here is the form http://swapmysim.o2.co.uk/
Did you come to O2 from another Network via a PAC Code. This again can take up to 24 hours to settle. If things continue then speak to the Network you have come from.
O2 Pac Code : http://service.o2.co.uk/IQ/SRVS/CGI-BIN/WEBCGI.EXE?New,Kb=Companion,question=ref(User):str(Mobile),CASE=31239
If your abroad do you have roaming turned on in the iPhone ?
Settings > Mobile > Data Roaming.
Do you have roaming activated on your account via speaking to O2 on 202 for Contract Customers or 4445 for Payg.
If your abroad right now the Cs numbers are :
Contract. : From abroad+44 844 809 0200 Free
Payg : From abroad+44 7860 980 202 International rates.
Remember your tariff allowances are for Uk use only so be wary of roaming charges.
Its best imo to stay on wifi and turn mobile data off or use a local Sim Card if your phone is unlocked to all networks.
If your pay monthly use O2's TuGo Service. http://www.o2.co.uk/apps/tu-go
If your abroad and you have everything set up then try manual settings to change the network in your phone as the network your latched to may itself be experiencing issues.
Text ACTIVE to 2020 , save the settings and then turn Airplane mode on and off.
Check your local masts for any known issue via inputting your full postcode here :
http://status.o2.co.uk/
Remove the sim and give it a wipe.
Other forms of reset of the iphone are :
press the top button and home button until the apple logo appears and let go of both.
And or ;
Settings > General > Reset > Reset network Settings.
Help links :
http://community.o2.co.uk/t5/Pay-Monthly-and-Pay-Go/Self-help-guide-Is-the-network-down-for-me-or-everyone/m-p/593752#U593752
http://community.o2.co.uk/t5/Apple-iOS-Devices-iPhone-iPad/Connecting-iPhone-to-Data-Services/m-p/544210#U544210
http://community.o2.co.uk/t5/Pay-Monthly-and-Pay-Go/International-Roaming-and-Whats-it-all-about/td-p/309678
O2 Travel : https://www.o2.co.uk/shop/international/using-phone-in-europe
O2 International Travel : http://www.o2.co.uk/international/internationalhub
