First, learn to embrace your data plan requirements. If your new phone requires you to pay for a monthly data component, take advantage of it. Developers have created free apps that use that data connection to make calls and send messages. That could mean you can get away with paying for fewer voice minutes or texts from your carrier. But the strategy only works if you have a smartphone.
If you do get a smartphone, you may be able to ditch you text plan. Instead of paying up to $20 a month for unlimited texting, try instant messaging apps like Yahoo! Messenger or AIM. They use as much data as an email -- practically nothing -- and are an easy way to cut your monthly bill by as much as a third. Just be warned, free apps may have annoying ads.
You can also save money but chatting over VoIP. Data-based voice services like Skype and Google Talk can cut minutes used, a big savings for people on prepaid plans. The per-minute cost is also cheaper for international calls. Savings could top $20 a month on your regular plan plus up to another $20 or so on international calls. But call quality may not be great, especially in areas where your connection is slow.
If you are in the process of relying on certain apps and smartphones, remember to broaden your network. These apps really only work well when the people you would be calling and testing can use them too. Skype is only free when you call another Skype account, and IMs go nowhere if we're not using the same app. If you're switching, enlist friends and family to try it too.
And finally, you will need to watch data usage. Data plan costs are more expensive than voice or text, so make sure switching doesn't push you over the limit. Most of these apps use very little data but someone who is also watching video on his phone or surfing the web could find this switch costly.
For more tips on how to save on your cell phone bill and other personal finance advice, visit SmartMoney.com