What will happen to my phone calls & text messages when I temporarily move the ATT SIM card from my iPhone to a Pixel/Android phone?

Hello rin.aus.

Thanks for reaching out to Apple Support Communities. We understand that you would like to know if you will continue to have service for calls and messages when switching your SIM card from an iPhone to an Android device. We will be glad to assist. Calls should continue on your Android device once it is activated with your SIM card inserted. Please see the following resource below for help with deregistering your iPhone so messages are sent to your Android:

Deregister iMessage on your iPhone or online

Additionally, your iPad should continue to receive any iMessages, as shown below also from the resource:

"If someone sends an iMessage to your Apple ID, you'll get it on your other Apple devices. If someone sends a text to your phone number, you'll get the message as an SMS/MMS only on your phone."

Cheers.

1) nothing will happen. Any SMS messages sent will be received by the new phone. Any old messages will stay on your old phone. The Android phone will not receive any iMessages.

2) nothing. The SMS messages and calls will stay on the Android phone.

3) ipads only receive iMessages, they cannot send or receive SMS messages without an associated iPhone.