I've been an OBI user for some time and have pieced together some somewhat sophisticated dial plans to keep in touch with family in UK and Canada for free - but am struggling with the notion of making use of "callback" as a working around to GV XMPP going away.
Maybe I have some wrong assumptions; but I thought I was seeing an implementation where when I dial a number via my VOIP provider (I have
voip.ms for calling international); and it somehow dials GV instead; which then makes use of the callback feature and GV behind the scenes connects the number I dialed with the phone I'm dialing from - thereby not using my VOIP outgoing minutes for entire call duration, but using my free incoming VOIP minutes instead?
Sort of getting lost on the concept how it works though; if above is correct does it use the smallest billing time slice to make the initial VOIP call - so for example it might round up to the first quarter minute for all outbound calls, then the rest of the call is the free incoming DID minutes?
Am I misunderstanding how it all works? I did spend some time researching call back - but not seeing something to defend or shoot down my assumptions.