I tried to use the Gigaset C530IP and the Grandstream DP750/720, and according to the tech guy I talked to, they could not communicate with my Obi202 to Google Voice because these phones were not SIP-compatible.
If I bought an Obi business phone, it would connect with a few clicks, but I haven't found any Obi home phones. The only phones recommended are legacy POTS phones.
So, is there anyone who has had success using a cordless IP phone (with HD Voice) and the Obi202 connected to Google? I'm surprised to learn I couldn't find any cases like mine in my searches. I'd really appreciate it if someone can point me in the right direction.