How do I prevent Google's voicemail from answering the call? (Asterisk)

Simon Telephonics states to do this as a fix
using FreePBX, set the context for your trunk to this custom context, entered into using FreePBX, set the context for your trunk to this custom context, entered into extensions_custom.conf::

[custom-gv-answer]
exten => _.,1,Answer()
exten => _.,n,Goto(from-pstn,${EXTEN},1)

I have placed the above in extensions_custom.conf:
have i missed something here
Like " set the context for your trunk to this custom context"
is there something i need to change in trunk settings?

I am trying to figure out how to isolate the call and get a full report on some of the
calls that do come through when soft phone is up.

Cdr reports indicate two apps i am unfamiliar with and not sure why the are involved
Playbacks & SayAlphas

2015-07-03 13:00:431435953643.115036832595Playbacks [from-pstn]ANSWERED00:05    
    
2015-07-03 12:52:151435953135.015036832595SayAlphas [from-pstn]ANSWERED00:17    
    
2015-07-02 17:56:121435884972.219712134260Congestions [from-sip-external]ANSWERED00:09    
    
2015-07-02 17:52:501435884770.119712134260Playbacks [from-sip-external]ANSWERED00:06    
    
2015-07-02 17:52:291435884749.019712134260Congestions [from-sip-external]ANSWERED00:13    
    
2015-07-02 14:54:411435874081.1httpCongestions [from-sip-external]ANSWERED00:12    
    
2015-07-01 18:59:521435802392.019712134260SayAlphas [from-pstn]ANSWERED00:11    
    
2015-07-01 18:13:181435799598.315036832595Congestions [from-sip-external]ANSWERED00:12    
    
2015-07-01 18:12:571435799577.217772498504101Congestions [from-sip-external]ANSWERED00:12    
    
2015-07-01 18:12:241435799544.117772498504101Congestions [from-sip-external]ANSWERED00:13    
    
2015-07-01 18:11:101435799470.017772498504101Congestions [from-sip-external]ANSWERED00:13