Yes, you can use the Konftel 300 if you only want to record a "local" meeting. 

Do the following: 

1. Press the LINE MODE button and select USB (you don't have to connect it to the computer) 

2. Press the green off hook button 

3. Start the recording by pressing the C/Rec button and confirm with "OK" on the Konftel 300. 

4. To stop the recording press the C/Rec button and confirm with "OK"