In your situation of GV & Obi100:
1.) Replace hardwired land line if you have one, see
here.
2.) In a hybrid twist of the above, port existing land line to GV, and you still have same number, ringing home phones, and no monthly phone bill from your land line provider, actual experiences
here.
3.) Use all the bells and whistles of GV, call routing based on
time of day/day of week, multiple
forward to phones, plus
Call Screening,
Audio caller ID and
ListenIn.
3.a) See detailed explanation below.
4.) Use all the * code features of the Obi, call waiting, call forward, etc. Link:
http://www.obihai.com/docs/OBiFeatureStarCodes.pdf.5.) Configure the 2nd SP service to add Caller Name (CNAM) to the GV supplied Caller ID (GV only gets you Caller ID, not Caller Name). Instructions
here. If desired also add 911 service.
And the really interesting part: Come back here to ask and learn once you get used to the device.
---- Edit 7-Oct to add ---------------
3.a.) Special Note for new users and GV Call Screening, Audio caller ID and Listen In as implemented on an Obi Device: These features, often referred to as 'call announce' and 'prompting,' work differently when a GV # is 'implemented' and answered directly through SPx service on an Obi device as compared to when answered on any other forwarding phone, such as a cell phone or hardwired land-line.
The short answer: You do not get the prompts on the Obi, and you have two choices: a) pick up phone to answer, call is immediately connected, no Audio caller ID, no ListenIn, or b.) pick up phone to answer, you get no voice prompts but you must remember to press 1 or 2 or else, even though you picked up phone (your phone is off-hood), caller still hears phone ringing and call will go to GV Voicemail unless you press 1 (or 2 and then *). The two choices a.) or b.) here are determined by the setting X_SkipCallScreening in conjunction with the GV
Call Screening option, which you must have set to "on."
The more complex answer: You use two SPx services and one physical Phone Port. Outgoing calls are handled directly by your GV # on SP1. Incoming calls to your GV # are forwarded to another VoIP number that rings SP2 and adds two features, adds CNAM to the call, and when answered through the Obi device the call to GV has the full GV voice prompting/call announce features. It's all invisible and works seamlessly. If you want a long-winded, drawn out discussion of it, see
here. Otherwise just follow 5.) above.