fyi: even receiving voice mail once a SIM is registered in a foreign network generally incurs a cost with EU carriers and is charged like a passive call in roam

fyi: even receiving voice mail once a SIM is registered in a foreign network generally incurs a cost with EU carriers and is charged like a passive call in roaming, even when the phone is subsequently turned off. the only way to reset this is for your SIM to register again with your home network. on a minor note, receiving return receipts is typically charged like an outbound SMS.