The minimum you need for wideband speech (aka "HD Speech) are two IP Phones that allow the use of a wideband CODEC such as G722, and an end to end transmission path that allows use of that same CODEC throughout. You could use:
OBi1022 ----- sip2sip ------ OBi1022
sip2sip calls are free and support G722.
Of course, this is limited as it is just a point to point system. However you can set up other voip providers such as GV or Callcentric /
voip.ms etc on your OBi1022. Then the OBi1022 decides which service to use depending on what digits you dial, or you can set up a speed dial to dial your brother that only uses sip2sip or other G722 voip provider.
The problem here is IP phones plug directly into the internet via your router. They do not connect to the normal house phone wiring. There are ways around this, but things can get complicated unless you are ok with the house phones being on a separate system to the IP phones.