Take a look at something I wrote up, the good news is you are so close to having what you want: Leveraging SNMP to detect your mobile device
What I think you need is the Map add-on and setup a .map file with the following in it:
1=ON
2=OFF
Then just slap :MAP(filename.map) to your item and OH should then translate the integers into the ON/OFF you want in Basic UI.