I'd cheat, personally.
There are quite a few 'faux-rotary' phones that have pushbuttons in a stylized rotary dial. Use those pushbuttons to subvert the keypad signals of a cellphone, and there ya go.
tons of room in the enclosure for stuff, too.
"No can brain today. Want cheezeburger."
From NGE: Nobody Dies, by Gregg Landsman
http://www.fanfiction.net/s/5579457/1/NGE_Nobody_Dies
There are quite a few 'faux-rotary' phones that have pushbuttons in a stylized rotary dial. Use those pushbuttons to subvert the keypad signals of a cellphone, and there ya go.
tons of room in the enclosure for stuff, too.
"No can brain today. Want cheezeburger."
From NGE: Nobody Dies, by Gregg Landsman
http://www.fanfiction.net/s/5579457/1/NGE_Nobody_Dies