You can draw a phone quickly with only using Rectangular Tool in Inkscape. There are 4 total objects and what you need to do is to round the corner correctly.
Since this is a flat illustration we dont have to draw it so detail but clear enough to represent the image.
Create a rectangle using Rectangular Tool (F4). Just make it like normal phone size in your canvas.
Drag the round handle on the corner to the bottom a little bit. Or as you see on my object properties: Rx: 0.000 Ry. 5.888
Create another rectangle as the screen. Draw it like the first one but smaller. You don’t need to round this one.
The third rectangle will represent the speaker. So we will just need to create a little rectangle above the screen object. Make the rectangle extends to the side.
The object position doesn’t have to be so centre since we have to put the last object beside it. But most phone actually have it right in the centre so you can put it as you like.
If you want to make it in the centre you can use Align and Distribute (Ctrl+Shift+A) to make it symmetrical. Choose Centre on Vertical Axis.
Still in Rectangle tool mode, drag the circle handle down very slightly.
The last rectangle, will represent the phone’s camera. Draw a square first. You can use Ctrl while drawing it to make a perfect square.
Drag the circle handle down about 30% of the square’s height.
It’s done. Yup it is easy drawing this little guy. I dont event use the Page Grid while drawing this phone. The next stage is coloring it.
I am using grey color on this phone vector. But remember that Phone color is actually have unlimited choices. Dont hesitate to use catchy, colorful/teenager color or soft ones.
Remove all strokes on the objects to make it look clean and the flat style will be more prominent.
Here is the final result.
I hope this guide helps you draw better in Inkscape.
And sorry for my english :)