As it took me some time yesterday evening, configuring those three to set an urgency hint for the terminal, so that my i3 highlights the workspace the urxvt containing the irssi-screen-session sECuRE told me I shall write a short post in order to help other finding the small glitches in their configuration which might cause problems.

screen: ~/.screenrc
Just turn the visualbell off:

vbell off

urxvt: ~/.Xdefaults
For urxvt you only have to activate the urgentOnBell option:

URxvt*urgentOnBell: true

If you use another terminal, you only have to search the documentation for "urgen" in order to find the option.

irssi: ~/.irssi/config
If you want to do configuration directly using the file, add these lines to the settings part:

settings = {
#...
  "fe-common/core" = {
    bell_beeps = "yes";
    beep_when_away = "yes";
    beep_when_window_active = "yes";
    beep_msg_level = "HILIGHT INVITES MSGS NOTICES CTCPS DCC DCCMSGS"
  }
}

Or using a running instance:

/set bell_beeps on
/set beep_when_away on
/set beep_when_window_active on
/set beep_msg_level HILIGHT INVITES MSGS NOTICES CTCPS DCC DCCMSGS
/save