Using google voice and hangouts connected I have a libpurple connection for hangouts in Bitlbee. I can send SMS through that connected interface via voice/hangouts. Works well for me (especially when in China on business)
I also live in Japan and travel to EU about once a month. Keeping in touch with my family/friends in US via my one phone number I've had since google voice launched is quite useful...
Pretty impressive. Any chance of tying it to IRSSI or making an IRC gateway like bitlbee? I connect to almost all those services through bitlbee already and it works pretty well. Add Naver Line support as well and I'm sold..