Aux question - why won't it mute for calls properly?

[CHUCK1]

2020 RT Limited not using bpr connect, using the aux port to xm radio. When receiving a phone call the audio input from the aux can not be lowered but the source must be turned off to mute. Only seems to happen when using xm through the aux, if streaming music through I Phone the audio is muted while on phone call. Anyone had any experience with this problem and have a fix?

[Bfromla]

Initially sounds like the IOS does the mute for phone calls not connect, might be something adjustable in settings

[CHUCK1]

I assume that when using the xm thru aux cable it will not mute through the phone. By the way I am located in Shreveport so we are neighbors.