mini HomePod pair won't connect to iPhone during phone call

During a phone call (or even before the dial tone begins), I will try to connect my iPhone to my connected/paired HomePod minis called the 'Dynamic Duo'. The Dynamic Duo never connects my call; I can't hear the person on the other line and they can't hear me.

If I play music, sometimes it skips rapidly through tracks, then playing something random.

How can I fix this?