how to swap O2 coverage to new iPhone SE from old iPhone SE

[Belsize]

Just got my new iphone SE with new SIM.  Loaded sim and xferred data from old phone.  All good.  Except old phone is still working (on O2 contract) with phone coverage and new phone showing 'no phone coverage service'.  What do I do?  Take the old sim out of old phone?  Cannot find set up instructions anywhere?!  Thanks if you can help. 

[O2Leyla]

Hello, yes you will need to remove old sim from old phone and put it into your new phone if it were an upgrade.

Hope this helps!

[Belsize]

Thank you for quick reply.  Only thing is - they sent me a new SIM.  So do I take the old one out anyway?

[Belsize]

I just want to move to my new iphone SE from the old one.  Currently the new one has wifi coverage and all appps etc transferred.  But no phone coverage - though I put the new nano sim in.  The old phone is still fully working!  Do O2 hve to do something? 

[O2Leyla]

If your old sim is working you can continue to use that sim in your new phone. I would keep the new sim just incase a sim swap has been requested but I doubt very much as your old sim would have stopped working if that was the case.

Hope this helps.