UPDATE: This issue has since been resolved so long as you have the latest iOS update.
I had noticed for some time that when using Siri to call someone on speakerphone, the call is made without using the speaker even though Siri would say she was calling the person on speaker. For example:
Me: “Siri, call mom on speaker”
Siri: “Calling mom on speaker”
But then… the call is made normally but without the speakerphone being used. Now, I can manually tap on the speakerphone icon and that works, so what could be causing this issue?
Wi-Fi calling. After going into Settings -> Phone -> Wi-Fi Calling and turning it off, I was immediately able to make a call on speakerphone with Siri.
I am not sure if there will be a fix for this issue, either through my carrier (T-Mobile) or through Apple (especially since this has been an issue since this feature was first released). Still, for anyone else who has this issue here is your fix.
Know something I don’t or have a question? Post below!