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Are you able to check your myvodafone to see if roaming is turned On.
Vodafone Live Chat can help you by checking at their end too.
Also try a soft reboot by turning the phone off and on.
Also go into your phones connection settings and choose another network and if necessary switch back tense if that kick starts anything.
Also check in your phones settings for any roaming settings / toggles.
Some Vodafone help in Using-our-network/Going-and-calling-abroad/Using-your-device-abroad.
Current Phone > Samsung Note 10+ 5G
Samsung One Ui 2.5 / Android 10.