Just tried this region free code and works fine for Samsung DVD-R155.

1. Press the Menu button on your remote control
2. Press 76884
3. The currently selected region will be indicated on the TV.
4. Press 9 button for multi-region playback.

Be sure to press the 9 button before your region code disappears.

Other Region codes:
RG1: 29334
RG2: 57538
RG3: 56732
RG4: 76884
RG5: 53814
RG6: 24462