Hi all - situation. 

My mum just got her first smart device - Google Nexus 5 (not 5X).  WeChat etc .. works fine with other people using smartphones except one of her sister in Canada who uses an iPad, she doesn't have a smartphone.  Probably in the past WeChat didn't require a phone number so she has it installed. 

With her Canada sister - she can call my mum fine.  She can also message my mum fine.  When my mum tries to call her it says "not WeChat friends". Mum can can message her without problems however. 

Any workarounds?  Is this because the iPad doesn't have a phone function? 

Thanks.