Are there smartphones or tablets where everything is connected to a single micro-USB connector?

Question

Iron

Many old phones (in particular, Motorola W208/218/230) use a single 3.5 jack connector both for connecting a headset and for connecting a data cable, and they themselves determined what was connected to them, and switched either audio or RS-232.
Question: is it possible to technically combine audio ports, RS-232 and USB-device in one micro-USB connector, so that the device itself determines what is plugged into the connector at a particular moment, and switches the corresponding port to it? Are there devices, or at least devkits, where this is implemented? (In principle, there can be only 4 connected "devices": a wired headset, data cable, charger and debug cable).

Answer 1

There used to be such a Fly phone, so it had a headset connected to microUSB.
There is no particular point in doing this - the mass consumer would like to be able to plug in their headphones (which are most likely equipped with a minijack), and not wrap themselves with adapters.
Implement - you can:

• RS232 can be detected by the voltage level -12V between RX and GND,
• Headphones - for low and symmetrical resistance r between GND and L; GND and R and twice the resistance 2r between L and R
• USB - by the presence of 5V between GND and + 5V

Answer 2

There is no such thing, and there is no special sense in this, in the context of what it was needed at all?

Answer 3

It is physically possible - a data cable, a debug cable and a charger already work via the USB protocol (the serial converter mode can be turned on either manually on the device or automatically under specified conditions), and I saw headsets with microUSB on some device. In practice, I did not hold such devices in my hands, but I will not argue that they do not exist.