Siri won't connect to contacts or make calls when using Assistive Access on iPhone

I am trying to help my 94 year old grandfather with terrible eyesight with his iPhone.

He likes the look of assisted access but he doesn't like that she won't connect to contacts and won't make calls or messages during this mode. I have Siri turned on for assisted access but she doesn't recognize any contacts and just says "to who?". I even tried assisted access on my phone and it won't work either. Is this a bug that can be fixed? My grandfather would really appreciate if it got fixed.

[Re-Titled by Moderator]

Original Title: siri in asissted access