No data connection without wifi

[Tervik]

Recently, about a week ago, my phone stopped making any data connection when away from a wifi signal.

I have used another sim card ( a friends TalkTalk ) and it works perfectly. Similarly, they have the same problem when my o2 sim card is placed in their phone.

[MI5]

@Tervik 

Have you used your data for the month? My O2

Or check guides:

Guide: Is the network down for me or everyone? 

https://www.o2.co.uk/apps/my-network

[Bambino]

@Tervik Might be an idea to get a new sim card. Call into an O2 store, if you have one nearby, and they'll do a swap for you. Be sure to bring photo ID when you go.