I do use google voice on my phone, but really just for voicemail. I use my G.V. # as a local number, and the out-of-state cell number as the old number that all my friends / family remember from the past. Occasionally I do have delays receiving G.V. voicemail txts & messages, so I'm slightly wary of using it to replace all the Sprint services. Maybe it's just the latency of downloading the audio...
I suppose I would make all my friends / family edit their address book if it came down to an extra $10 or $20 per month!
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I do sympathize with your situation. I've had to consider (for complicated reasons) leaving the old plan that I'm currently on & it looks like pretty much every phone company wants to charge well over $70/month for a smartphone with a dataplan.
I avoided getting a smartphone for 3 years because I didn't want to be paying $70+/month a cell phone bill...And I absolutely won't.
I still think of the 4 major carriers, Sprint offers one of the best value.
If they got rid of their $10/month 3/4G tax today, I'd move over to them ASAP instantly.
Regarding T-Mobile's "Value" plans...If they get swallowed by AT&T, would AT&T still have to abide by the agreement?
I don't have a problem spending $600 on a smartphone every 2 years like the value plan requires...and yes, I know it's not true unlimited since you get cut down to 2G speeds after passing the 2GB mark.