My mother has a postpaid plan. She’s currently in China and mainly just needs to receive text messages for 2FA. Maybe she’ll send a text or two at some point. 

To avoid data charges, she’s got iphone Cellular Data turned off. 

EasyRoam is NOT added on.

What IS showing on the Add-ons are: International Data Roaming … and International Voice Roaming are included

But she’s unable to receive any text messages. 

I spent an hour with Koodo customer service/tech support today and was told that phones nowadays require data even for texting. That the only solution is to turn Cellular Data ON. However, my mom is reluctant to test and be subject to the $10/MB pay-per-use if it accidentally incurs data. And I find this advice dubious anyway.

What’s the real issue / solution here? Or is tech support guy right?