Unable to make voice calls on new phone

[Dwarf]

Hi I'm looking for some help if possible I've recently received a new handset and 5g sim for an upgrade b4 this my old phone (iphone) worked perfectly after the new sim swap (done by me the o2 shop and online ) the new handset will not allow calls it just says call ended without dialing, if called I get number withheld all other functions on the phone  work , if I go into the sim status it says mobile network state disconnected service state saying in service . There are no diverts or bars active so phone should dial any help would be much appreciated 

[Dwarf]

No still unfortunately theres still no active voice calls tried again with an advisor who rang me but as usual they recommended the shop again which cannot help with the problem asked to speak to a manager to try to escalate to tech repair team but was told no managers available and yet again wait 3 more days