How Do I get to know which com port my USB modem is connected to? Is there any command?

Question

Please help me i am unable to connect to internet. When i connect using network manager i connects only once the it does not detect my modem.

Answer 1

You can get a tree of USB devices with lsusb -t

/:  Bus 05.Port 1: Dev 1, Class=root_hub, Driver=uhci_hcd/2p, 12M
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=uhci_hcd/2p, 12M
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=uhci_hcd/2p, 12M
    |__ Port 1: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid, 12M
    |__ Port 1: Dev 2, If 1, Class=Human Interface Device, Driver=usbhid, 12M
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=uhci_hcd/2p, 12M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/8p, 480M

True serial ports can be detected with the command dmesg | grep tty

[    0.000000] console [tty0] enabled
[    0.526866] 00:07: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A

You can set and/or report serial information with sudo setserial -g /dev/ttyS[0123]

/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
/dev/ttyS1, UART: unknown, Port: 0x02f8, IRQ: 3
/dev/ttyS2, UART: unknown, Port: 0x03e8, IRQ: 4
/dev/ttyS3, UART: unknown, Port: 0x02e8, IRQ: 3

if setserial isn't installed already you can install it with sudo apt-get install setserial

Answer 2

Execute following command in terminal :

lsusb

It will look like this

You see the device 004 : .... shows logitech Inc, it is the port where my usb mouse is attached, check your usb devices and see the name of your modem corresponding to device 00X.

Check this for more info