Free VOIP calls, reliable even on 3g mobile data connection
There are several free VOIP solutions such as grooveip lite but they all suffer from bad quality on 3g. I found a clever way to make free and reliable internet (VOIP) calls even on 3g mobile data. I posted the full instruction on XDA forum.
It's complicated but it's how I can get great call quality on 3g data. I'm relying on VOIP 100% as I disabled Google Voice forwarding to my cell number.
Now I'm paying $30/m for 2000 minutes and 5GB data.
PS: Please do not suggest Groove IP or talkatone. Theoretically, these work on 3g but in real life, it's not usable. If you can get great call quality using these apps, then consider yourself extremely lucky.