What is the exact message?
Did you activate the replacement SIM?
All I can suggest is you try the new SIM in another unlocked phone if possible.
If it works there then the problem is the phone and you'll need to contact Argos or Alcatel support for more assistance.
I cannot find anything useful when Googling the phone make and model and either of those error messages.
Did you try contacting 48 support also?
By the way - just to eliminate one other thing - you are inserting the SIM correctly - i.e. so that the SIM contacts make contact with the SIM tray contacts?!
Apologies if that sounds stupid but some people have managed to do it the wrong way...
To be honest the behaviour of the phone so far suggests to me that it is locked to some network even if it should not be.
I'd be inclined to go back to Argos and ask to try another one or something like that.
You mean it's now working in your new Alcatel Pixi 4?!
That's great - even if it's still a bit mysterious!
Anyway - glad it's working if that's the case now.
Remember to configure your internet settings if you have a data allowance that you want to use:
Hope this helps.