Setting the Number of Rings on Google Voice
Google Voice has a set amount of time before callers are routed to voice mail; if after 25 seconds you haven't picked up, the call will be sent to your voice mail. You can adjust the number of rings on your mobile or home phone before it goes to voice mail to prevent calls going to the wrong voice mail service.
1 Google Voice Overview
The idea behind Google Voice is that you can have one phone number that you give out to people and it rings any or all of your phones when you have an incoming call. The benefit is that you don't have to set up call forwarding for each number and you can change mobile or office numbers without having to update all your friends and family, but the idiosyncrasies can take some adjustment, including the voice mail interface.
2 Google Voice Voice Mail
It takes 25 seconds for a call that comes in to Google Voice to be sent to voice mail, but if your mobile phone or your home phone is set to go to voice mail in less time than that, all your messages will end up scattered across your different phones instead of searchable through the Google Voice app and website. The solution isn't to reduce the number of rings for Google Voice but to increase the number of rings for your phones.
3 Number of Rings Needed
Even though mobile and electronic phones don't need to use the standard analog ringing signal, most still do for the sake of consistency. The North American ringing cadence is for a ring that lasts for two seconds and then is off for four seconds, so each ring totals six seconds. To ensure that you have more than 25 seconds of ringing time you'll need your mobile phone or home phone to ring for at least five times.
4 Turn Off Voice Mail
Another option is to simply disable the voice mail on your mobile phone or home phone so that you don't have to worry about scattered voice mails. You won't be able to do this if you share a landline with other people, but it works well on a mobile phone so you don't have to set up a voice mail account on your phone in addition to your Google Voice voice mail.