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I have an iPhone XS Max and an iPhone X. For over a year now, I’ve been able to respond and send iMessages and SMS on either phone. This feature stopped working and it’s made me want to pull my hair out.

For example, if you have two active SIM cards in two seperate iPhones and you are sycning them together using “Text Message Forwarding” you will recieve SMS messages for both SIM cards on both phones. This can be very convenient for business phones. Unfortunately, if I want to reply to the business-related message conversation using your business line, I now have to switch to that line or I can reply with my “Primary” line, but the recipient of the message will likely see it as a reply message from another number.

I’ve turned off iMessage, turned it back on, did a factory reset through iTunes on both phones, etc. nothing works. Does anyone have any idea how to fix this? Apple support has been of no help.