Welcome to Vodafone Community
On my first trip abroad and my a message on my phone pops up everytime I try to call or text "phone not registered" "SIM not allowed to join this network" , I'm with vodaphone UK and this is trying to Join vodaphone Ireland, any help would be much appreciated as I can't phone customer service.
Check that your phone isn’t barred for use abroad using the My Vodafone app or My Vodafone online.
Even though Vodafone Ireland use the same Vodafone name they are not linked to Vodafone uk.
Unfortunately when roaming Vodafone UK cannot guarantee everything will work. They have no access to another Vodafone Network.
A person can try and self help troubleshooting via choosing a different network in their phones connection settings etc.
Also the masts where you are could be experiencing issues and or mast congestion.
The issue is Vodafone Uk cannot access to check.
They should have an online mast checking service if you can access it somehow.
Vodafone uk customer services on the phone or via Live Chat can however check your account. vodafone uk/contact-us.
If your phone is unlocked to all network's then as an interim solution you could choose to use a local sim card.
I wish you all the best with this situation.
Current Phone > Samsung Note 20 5G - SM9860 Snapdragon.
Samsung One Ui 2.5 / Android 10.