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If you have a Big Value bundle, it would depend on the number of inclusive minutes.
The my Vodafone application will give information on minutes remaining from your bundle and extra credit.
Also further information available from the website on this link: How can I check my Pay as you go balance?
Mobile networks are not line some UK Landline companies where one has to hang up say after 1 hour @b4u2
You can keep going as long as your credit or minutes allowance last.
Current Phone > Samsung Note 10+ 5G _256Gb > Model: SM-N976B.
Samsung One Ui 2.0 / Android 10.
Samsung Gear s3 Frontier Watch.