I kinda disagree with most of the posters above. I don't know anyone that does this, but I think you can use the iPod Touch with Skype or some other VoIP service that basically makes it into a phone (only on wifi though).
I have read on other threads that people use their 3G/4G/LTE iPads (with Skype or whatever) as their primary phones. Saves on the $80+ monthly bills. So yeah, I think you could say the 4G/LTE iPad = poor man's iPhone.
Hello, I'm someone who does this. So now you know someone. Prior to iPad Mini with LTE, I used an iPod touch as a "poor man's iPhone". VOIP apps like Skype, Talkatone, etc paired with either device is a great alternative to $100/month iPhone service plans with only a modest tradeoff in the anytime/anywhere convenience of an actual iPhone. In my own case, the vast majority of the time, I'm around available wifi, so it "just works".
Where it comes up short is when I'm away from wifi (though if I really need to take/make a call in such scenarios, I can always turn on the LTE in the iPad Mini for a one-time, much cheaper cost... or I could turn on the mifi device to cover this when iPod Touch was the option but I rarely have to do that), or when I'd like to make/take a call in motion such as riding around in a car.
As previously offered, if one doesn't feel the need to immediately send/receive the "what R U doin?" texts and/or calls (if the phone-side communications can wait until you are in a wifi zone by tapping options like voice mail and just queing up text messages), this is a great way to go. When I've had a "real" cell phone in the past, I've generally had it turned off much of the time to keep the interruptions of calls/texts manageable, so this is almost no different for my purposes.
iPad Mini with LTE + Skype + Talkatone + Earbuds with Microphone is an excellent "poor man's iPhone". The LTE piece can be used only when absolutely needed and for only a fraction of a single month's iPhone cell service toll. To accomplish the same with an iPod Touch, it takes the same kinds of apps, the same earbuds + mic and maybe a mifi device with on-demand 4G/3G for similar "emergency" (away from wifi and need to take/make a call) scenarios. Either way, the total cost is much, MUCH less than going the 2-year-contract way. For those who are generally in a wifi zone much of their day, you can probably avoid ever using any 3G/4G and thus your monthly toll can stay at $0. Should you have an emergency situation and no wifi can be found, turning on 3G/4G for that situation can be as little as $20 ONE TIME.
Is this for everyone? No. If you need to receive "what R U doin?" texts immediately when they are sent, this isn't for you unless you are
always in a wifi zone. If you need to take and make calls anytime/anywhere, this is also not for you unless your "anywheres" are always in wifi zones. If $100/month for service whether you really need it or not is no big deal to you, then that $100/month does buy anytime/anywhere 24/7 convenience even in motion. If you are a "keep up with Joneses" type, obviously an iPhone is not the same as an iPod or iPad (but those types usually have up to all 3 anyway... and must upgrade to the latest versions even if the old version does everything they need... and gripe when the outer shell doesn’t look different enough so that it is obvious to anyone else that they have the latest version).
For everyone else, AT&T, Verizon, etc appreciates your $100/month payments even if an alternative like an iPod or iPad could cover your needs about as well.