AT&T just introduced a new family plan for wireless customers. It's the latest move in the carrier's\u00a0battle for your business. The new plan is cheaper than previous AT&T plans, and AT&T claims the new plan is cheaper than those offered by Verizon.\n\tAll of these family plans have so much fine print that your costs can vary greatly depending on the options you choose. It\u2019s also important to know that almost all of the new plans offered by the four major carriers require customers to pay the full retail price for smartphones, and that means shelling out hundreds of dollars more than you would have under the old-style, two-year contracts.\n\tThe chart below shows the basics of what AT&T calls the new \u201cMobile Share Value Plan."\u00a0\n\t(Chart via AT&T)\n\tA family of four would spend $160 a month to share 10GB of data, while the same family would spend $260 a month for 10GB of data from Verizon. Both carriers will also sell you more data per month if you want it. But you also need to spend another $15 per device for a monthly service fee, so a family of four would actually spend $220 a month on AT&T ($160 plus $60 in service fees), and that's not including various taxes and fees that are added on. Plans from both companies include unlimited talk and texts.\n\tNew customers are, of course, eligible for AT&T's new plan.\u00a0 You can bring your own unlocked phone; but first check with AT&T to be sure your device is compatible with AT&T's network. You can also buy a new phone. If, for example, you want a 16GB version of Apple\u2019s iPhone 5s, it will cost you $649. You can either pay that upfront, or choose to pay it off over a period of time \u2013 without interest.\n\tIf you\u2019re already an AT&T customer you can switch over to the Mobile Share program. Note that if you do switch over, you have to become part of the AT&T Next plan (I told you this was complicated), which means when you upgrade, you pay full price for a new phone. If you'd rather not do that, this plan probably isn't for you.\n\tAT&T is sweetening the deal for both new and existing customers by giving them a credit of $100 per device on the new plan, as long as they stay active for at least 45 days.\n\tGot all that? Well, what I just said about AT&T\u2019s plan will be true for a while, at least, but it wouldn\u2019t surprise me at all if Verizon comes back with a counter-offer. Over the last six months or so, all of the major carriers have finally moved into the competitive mode and are constantly trying to undersell their rivals.\n\tThat\u2019s great for consumers. But the plans are all fairly complicated, perhaps deliberately so, and the onus is on you to read the fine print really carefully.