This box uses the Nokia32 IR protocol, device 35.64.

The 15-2133 is way too old to have a setup code for this.  Newer remotes can use setup code Cable 0858.  If the modem in your 15-2133 still works, we may be able to provide you with a WAV file to upgrade it.  Or get a RCA RCRP05B, which is < $20.