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You need to contact the network you bought your phone from asn ask them for the unlock code otherwise the vodafone sim (or any other network sim) wont work.
Apologies for the delay in responding, we experienced a high volume of queries.
I'm afraid cookie is correct, if your handset is network locked, you will be required to get in touch with the provider who sold you this device and request your handset unlock code. Once you have this and your handset has been unlocked, you should be good to go with your new Vodafone Ireland SIM card.
If you have any further questions, please don't hesitate to contact us here.