I’ve noticed that my iPhone switches inexplicably to playing the notifications through the to-ear speaker (which is of course virtually 100% inaudible when driving) instead of the speakerphone. This has caused me a fair amount of missed rides/frustration but I believe I found the solution last week.

I use the online/offline sounds to check for this issue regularly. If they play through the speaker, all is well.

If they do NOT, I've found that calling myself/any number with the phone app and immediately switching the call to speakerphone mode before ending it to be a 100% reliable fix so far.

Vid is just to help you visualize the process since I know my instructions sound confusing.