Can I use iMessage or chat features (RCS) without a data plan?
To use iMessage or chat features (RCS) you need an internet connection (with a Shaw Mobile data plan or WiFi).
Without a data plan or WiFi connection, you will get an error message while sending. Your Messages app may prompt you to “Send as Text Message” or “Switch to text (SMS/MMS)”.
Group Messaging with MMS is a great alternative to iMessage or chat features, and doesn't require a subscription to a data plan (though you will need to make sure that your data connection is enabled for it to work).