Google Voice Trunk answers incoming calls before user does


I setup Google Voice Trunks in FreePBX (under Other-Google Voice). However, whenever there is an incoming call, the GV Trunk answers it IMMEDIATELY, and then rings the final destination extension. If the user at extension takes a long time to answer, the caller has to pay phone bills for all that time he spent waiting. And if they never answer, the Google Voicemail never gets a chance to pick up the phone. Also, any other destinations in GV that are also supposed to ring, such as cell phones, never get to know about the incoming call.

The solution mentioned at the page below works well:

However, as soon as any change is made in settings anywhere in FreePBX, the file extensions_additional.conf gets overwritten to the original code and the problem returns.

Could someone suggest a more permanent solution?