Here's an old model phone that I made for a prop in our school's play. The gap at the connection in the original model (pictured) between the base and upper post has since been fixed and should fit together without problems.

Designed in Openscad. Sliced with Kisslicer. Printed without supports on all pieces, even the ear piece. The bridging over the inside of the ear piece actually ended up looking like a screen to hear from.

I printed at .25 m layer height and 20% infill and everything came out well.

If your machine doesn't bridge well or if you would like a smooth bottom on the ear piece enable supports however this will tend to support the rounded edges which should be able to print without them.