I'm just diving into the details of the smartphone and data plan world. So here is my plan. Let me know if I'm getting off-track somewhere.
T-mobile, non-contract, voice and text only, 3 lines.
3 new smartphones and data plan for all at lowest reasonable cost for good service.
No change to how others contact us (our phone numbers for voice and texting stay the same).
Not pay for separate texting plan from carrier AND no complicated steps for texting (Wife needs simple).
Have all 3 lines ported to Google Voice. This cancels current cell service with T-mobile.
Get new phones and service (probably Verizon) with data and 3 new phone numbers. NO TEXT MESSAGE PLAN!
Have GV forward all calls to new phone numbers. Setup GV to handle text messaging.
That can work, but you'll probably find that texting costs a lot less than data (except when you have wifi), and it's hard to find any plan that doesn't include texting. At any rate, I recommend Page Plus Cellular. They let you use most Verizon-compatible phones (including smartphones) and have very competitive rates. You can check out the Page Plus forum for more info.
Page Plus looks good for a single line but with 3 lines... not so much. I also get a pretty good discount with the major carriers through my wife's employer. So far it looks like Verizon is the only carrier with good signal in my area and they charge $30 a month for texting. Sprint is the only carrier I have not physically tested, but they are not known for strong signals around here so I will likely be going with Verizon.
Here is what I did to save money. I plan on spending no more than $50 per year on my phone plan.
1. go to craigslist and buy an att or tmobile (if you live in the US) android smartphone that is or can be rooted. any gsm phone will work. an iphone should work too, although i haven't tried it.
2. root it if it isn't already (this can be quite the process depending on the phone and your computer skills)
3. port your current phone number to google voice.
4. get a pre-paid pay as you go t-mobile sim card and put $100 on it. buying $100 of minutes the first time keeps the minutes active for a whole year. after your first purchase, you can buy any amount and they will be good for a whole year.
5. download the groove ip app for android (make sure you get the paid version that integrates with your phone's native dialer). use this app to make most of your calls while you're connected to wifi. make sure to set google voice to forward your calls to your t-mobile number, so you still get calls when you're not in a wifi area.
6. download the google voice app for android and use it over wifi for all your texting needs. also, set google voice to "make all calls using google voice". by doing this, when you're not on wifi, when you make a call, the phone automatically detects that it can't use groove ip and uses google voice instead. in this way, the people you call will only ever see your google voice number displayed.
Benifits of this setup:
extremely cheap smartphone usage. I got my phone for free from my dad, and I plan on spending about $50 per year (after the initial $100) for calling minutes and texting when i'm out of wifi range. many people spend well over $1000 per year for their phone and plan. of course the cost of home broadband is a consideration, but many people pay for this in addition to their mobile plan.
complete freedom to use t-mobile or any other gsm carrier's prepaid plans without porting numbers. Just beware, I have heard that some carriers auto-detect your smart phone and try to make you buy a data plan. t-mobile does not do this.
no mobile data unless you find a wifi network.
switching google voice to forward text messages to your phone number when you are not on wifi is a bit of a process. i usually forgot to make the switch and thus do not receive text messages when i'm not connected to wifi. if you don't mind spending a little more money, you could keep the forward text messages setting on, thus receiving the message both in your google voice app and on your phone's messaging app.
google voice does not support mms. i never use mms anyway, but some people might care. you could still send mms using your t-mobile phone number, but this would probably confuse your friends.
But the wife wants to use data wherever she is. Particularly while out-and-about on weekends and on vacation. Also, T-mobile and AT&T signal sucks in my area, outside of the metropolitan area.
We can easily afford to pay for the service and phones, I just try to be as frugal as possible without undue hassle. Going through Google Voice setup is a significant hassle, but $30 a month is a significant amount of money in my mind and worth some hassle. $360 a year is a good chunk of change!
I've been with TMo a long time. Can't beat the value. But easy to beat the signal coverage. We've gotten tired of having to say "Call me back, I'm about to hit a dead spot". Or hitting one of the "iffy" areas and hoping the call doesn't drop this time. If I'm going to be spending the bucks on a data plan I want it to work and Verizon simply works. I just hope they start the family shared data plans soon.
Phones arrive this week so I'll find out soon enough how well the this alternative texting works.