I have an a71 phone. Just switched providers to Freedom Mobile. They say they can't help me. Receiving group texts (Canada and USA friends combined) but cannot reply. In Canada, no problem messaging between Canadian friends.
Thanks for reaching out. Support for US products is the focus of this forum. As your device is a non-US model information is severely limited. We kindly suggest that you use this link to look for a support team in the area your product was manufactured in: https://www.samsung.com/us/common/visitlocation.html
Additionally, if you scroll to the bottom of the page on the website for your region, you might discover that your nation provides its very own support forums, just like this one! Just look for the Community Option.
