If you have Wi-Fi, you can cut your monthly mobile bill to nothing. Thinkstock By Miriam Cross, Associate Editor From Kiplinger's Personal Finance, August 2015 Imagine calling, texting and surfing the Web for a few dollars a month—or even free. The catch? You must rely primarily on Wi-Fi hotspots instead of a cellular network.See Also: Best Cell Phone Plans for Every Type of User FreedomPop and Scratch Wireless both offer a basic package that costs nothing. Republic Wireless charges $5 a month for Wi-Fi–only mobile service. Cablevision and Google recently debuted similar plans. Freewheel charges $9.95 a month for Cablevision customers, $29.95 for all others. Google’s Project Fi, available by requesting an invitation, costs $20 a month. Price depends on the connectivity and services you choose. All except Freewheel include, or let you add at an additional cost, traditional cellular service as a backup for those times when you’re not in a Wi-Fi zone. You’ll be bumped to Sprint’s network, or, with some plans, to T-Mobile’s. Those add-ons are where the savings start to diminish. Opting for more gigabytes or higher data speeds can boost the price of a plan to $40 a month or more. Plus, in most cases you have to buy one of the company’s designated smartphones. Advertisement Before you switch carriers, assess your proximity to Wi-Fi on a regular basis and the backup carrier’s coverage in your area. Each service is customizable in a different way, so dig for perks that work for you. Project Fi gives refunds for unused data (and, soon, so will Republic). FreedomPop lets you bring your own phone from a select list. For Ryan Savara, who enrolled in Republic’s $25-per-month plan, affordability is key. The Central Michigan University student is usually connected to campus Wi-Fi, but he relies on Republic’s cellular service to fill in the gaps. “For unlimited everything, it’s a deal,” he says.