I just recently got a Nexus S and activated it with Ting, and am loving it: finally, the freedom to use smartphone without paying tons of $$$!
I'm using Google Voice to make calls (via voice) and text (via data). However, today --- just my second day since activation -- I got an error when trying to pull up the GV app, stating that it couldn't sign into the network. Data was working: I was able to pull up the mobile version of the GV site and see the texts that I'd received. But the GV app wasn't working.
Prior to that, I'd turned off background data for everything but GV, Gmail, Contacts, Calendar and Android Services, meaning that I'd turned off background data for Google Services. When I got back home to my wifi network, GV connected fine and sent and downloaded my texts.
So I'm wondering... are there any apps that I *need* to keep running in the background in order for GV to work properly, apart from GV itself?