Although a gadget it’s not that practical, I'm really happy that this Star Trek replica prop, a personal favourite, has become more and more realistic of late.
A production prop replica of the original series communicator has gone on sale. When you connect with an iPhone via Bluetooth for instance, you can also use to take a call. Flipping open will also answer the call!
​ ​It is also pretty good as a production prop!

Star Trek TOS Bluetooth Communicator