Cannot add Outgoing COM port for any android device My problem is that I need to add outgoing com port to my android device (Nexus 4) Windows 8 x64 connected via Bluetooth. 

This is usually done by using Bluetooth settings on the PC and then from "COM ports" tab yo "Add" -> "Outgoing port". However, when I try to add my device it shows me error "The device you have selected does not have a serial port service running". For Incoming port it work fine, but that's not the option I need.

I've also tried to connect Samsung Galaxy S3, Nexus 7 and rooted Nexus 4. Both on Windows 8 x64 and Windows 7 x32. Nothing worked. Then I connected an old phone which uses Symbian 8(?) and it worked fine. Of course the devices are paired before I try do add COM port.

I did good search on Google, but I did not find a way to "turn on serial port service". There's an app (Serial Port API Sample) which supposedly should help with my problem, but it doesn't - I can't get it to work, always showing an error.

I need the outgoing port so I can control my device like a modem by using Matlab.
This is just based on a bit of research, not my own experience:

Android phones, unlike your Symbian phone which worked, do not expose a Hayes-command modem as a built-in externally accessible service. There may well be such an interface internally for communicating with the “baseband processor”, but in order to control it from another computer you will have to install an Android app and/or modified OS which forwards the commands it receives from an external source. I don't know whether such an app already exists.

(Further questions on how to get the scheme I described working might be better asked over at Stack Overflow as they would be essentially about programming Android.)