Currently use mainly my iphone, on Vodafone. Have a Telecom home line, but hardly use it. As I have lots of family and friends overseas, I use Skype (from PC, iPhone and Mac) & WhatsApp to stay in touch. Doesn't always work (Skype on 3G not always great) so I do make regular international calls from my mobile.
I have a Uniden cordless phone for my homeline. My mobile is a secondhand iPhone 3GS (with Orcon). I sometimes use Viber to make free calls and texts on my iPhone. Otherwise, I use Skype on my computer to make free webchat calls to my folks back in the States.
Use 2talk at for home calling and Bria in iPhone with InPhonex or 2talk iPhone app for VoIP calling. Occaionally use Viber. I also had a play with Babaoo which I think is an awesome concept but the voice quality is average. I downloaded this Vonage app when it first came out but then decided that I'm pretty much covered for VoIP calling from mobile
Nokia 3200 on 2degrees prepay. A 3200 was used in Dr Who by Rose Tyler. My 3200 has the DOOM intro/level one theme midi file as the ring tone I would try Time to Call if it was cost effective and easy to load credit onto (i.e. simpler than Skype). I have naked DSL and I very occasionally use skype.
I'm using an iPhone <waits for the groans to die down> after using an Android phone for a couple of years. I would DEFINITELY try Time to Call, it sounds awesome; currently paying Telecom for a few important numbers we call regularly.