USB Modem Permission on Linux

I have usb modem and want to play with it’s AT Command. In Ubuntu 10.04 I could access the modem easily without problem as regular user.  I choose to install Centos 6 to test my modem. Centos 6 has no problem recognizing my usb modem which has PL2303 controller.

I try to use Kannel 1.4.3 which I get it from EPEL repository and successfully installed, when I try to fire up bearer box I got this

DEBUG: AT2[modem1]: detecting modem type
INFO: AT2[modem1]: opening device
ERROR: AT2[modem1]: open failed! ERRNO=13
ERROR: System error 13: Permission denied
INFO: AT2[modem1]: Closing device

As usual, googling the solution and most of resource I found was getting hardcore modification and adding user to a group. Specifically, adding regular user in uucp groups, still it doesn’t work.

I remember when I was tried to connect to the network on Debian i got same problem and the solution is

usermod -a -G dialout nurasto

Now, my regular user can use usb modem as sms gateway without problem. 😀