Voip GSM gateway with android phone hack?

Hiho! Apart from all-in-one hardware solutions to bridge voip outgoing calls to the GSM network (like goip-1) is there a hack that would allow me to do the same thing by connecting an existing openwrt flashed router to an andoid phone through and USB connection?

This is a follow up.

  1. according to threads I've read on the Net, Android APIs do not allow voice redirection through wifi, only through BT. But this info may be outdated
  2. More importantly, my cellular provider has been recently bought by another company and they now support WIFI calling, so there is no point in doing this anymore!