Issue with Default Voice Line Setting and Recently Used SIM Behavior

Hello everybody,

I recently switched to an iPhone 16 Pro from Android, and I’ve encountered an inconvenience with the dual SIM functionality that I’d like to address.

I live in Country A and come from Country B, so have one SIM for Country A (SIM #1) and another for Country B (SIM #2). I’ve set a "default voice line" in the settings to choose which SIM should be used by default for calls (let's say SIM #2). However, I’ve noticed that when I make a call to a contact for the first time (let's say with SIM #1), iOS automatically assigns the "recently used" SIM #1 for subsequent calls to that contact, regardless of the globally set default voice line (i.e., SIM #2).

This behavior persists unless I manually set a default SIM for each contact, which I don’t want to do. My expectation is that the global "default voice line" should take precedence unless a specific default is assigned to a contact. This issue is frustrating as it adds unnecessary complexity.

On my previous Android devices, the global default SIM was always applied unless explicitly overridden for a specific contact. I find this approach much more logical and user-friendly.

I’ve searched the Apple Support Community for similar posts but haven’t found a solution to this issue (if any).

Is there any way to ensure that the global "default voice line" setting is always respected unless I manually assign a default SIM to a contact?

Thank you for your assistance and best regards!