What other things could influence the style of the object

I think there are many factors that have influenced the style of the telephone over the years. The first one was created to transmit sound at a distance. I believe when developing the style of the object they had to take into consideration the different types of people using this object. Age, disabilities such as blindness and deafness would have been a factor.

On this website there are many different types of telephones for the blind and people who are hearing impaired. https://assistech.com/store/telephones-for-the-blind-and-visually-impaired

With the new smart phones you can go hands free and command the virtual assistant to call people, send msg, book appointments, send emails and so on.

https://learningenglish.voanews.com/a/deaf-blind-woman-first-to-use-new-phone/2777539.html
In 2013 a woman in Australia who is blind and has poor hearing was the first person to use a braille phone.