how to set permission to device /dev/rfcomm0 ?

I am trying to run kannel bearer box but i got error something like could not write/read device. I think kannel doest have permission to read/write bluetooth device /dev/rfcomm0

Thanks for reading. Any help would be appreciated.

From stackoverflow

• with root account do

  chmod a+rw /dev/rfcomm0
  

• If you know which program is generating the error message, run the program with strace and see which system call yields the error. If it's open, then the chmod solution recommended by Francis should do the trick. If it's read or write, then you should investigate further: is there a problem in the kernel or the appication code.