iphone xs max dual sim problem: calls gets disconnected or very low voice quality second sim

I have been using my iphone xs max (physical sim) for a year now. My work number is being used for mobile data, calls, facetime & imessage, while my personal number as a secondary physical sim.

Since I bought this phone I'm facing problems on my 2nd SIM, people often can't reach me on the personal number, if reach me than the call disconnected or voice quality is so bad that I can't even hear them nor they can hear me properly.

I've complained this issue to my service provider cellular company and they informed me that this issue longs to apple and have already complained to apple as well.

Now I've been waiting since long that apple will resolve the issue in any updates but nothing even happened in the IOS 13 or later versions and still facing the same calls quality problem.

Can someone inform me when this issue will be resolved? or should i change my phone back to SAMSUNG?

Your quick response would be highly appreciate.