Hey @Geluk, welcome to Three Community.
The terms and conditions of our Pay As You Go SIMs require that a chargeable event or activity is made at least once within a 180 day period, to keep the account active. Chargeable events include making a call, sending a text or picture message, or using data (or any other Three Service for which a charge is made).
As receiving most calls and texts doesn't use any of your allowances or credit, this wouldn't count as a chargeable event or activity.
I hope that helps clears things up, but please let us know if you've any other questions!
StephR
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