iPhone 15 Pro Max iPhone and Dual SIM. Still doesn't work!!

[antisomnic]

I have had dual sim since my iPhone 11 Pro Max. I have a business line and a personal line. I would like for neither the two to mix. Am I doing something wrong? I've had the 11pm, 13pm, and now the 15pm, and every once in a while when I am texting a a client on my business line, it randomly switches to my personal line. The contact says always use the business line. I try deleting the thread and starting over, still nothing.

It confuses my customers and I'm not a fan of them having my personal number. This has occurred over the last 3 phones I've had so it's either a software issue or I'm doing something wrong. PLEASE HELP!

 

[Lammy]

Are you generating a new message when it happens? Or are you already in the conversation and just typing in the box? I’ve noticed mine will change sometimes when I generate a new message due to the “start new conversations from” setting in messages.

 

[antisomnic]

It occurs while I'm already in a thread. I'll send a message and it'll randomly say "Switched to Primary (the name of my personal line)" First thing I always do is check what the contacts line is and it's always my business line.