Is it possible to have multiple OBI202 using one google voice email account ?
then the ports from these OBI202s goes to a voicemail system ?
Yes, that is exactly how things work. You can have multiple OBi devices (in fact, any OBi product that supports Google Voice), connected to the same Google account. All will ring at the same time, and all will go to Google Voice voicemail if not answered.
I just want one port ring to a voicemail port - not every ports on all the OBI202
is it possible ?
Sorry, but not with Google Voice. Use a SIP VoIP service provider, instead.
Any recommendation for cheapest SIP VOIP provider - since all call are incoming
You can get a free inbound telephone number located in New York State, from Callcentric. If you want a number local to some other place, voip.ms, Anveo and Callcentric are all very good choices, and all of them work fine with OBi products.