Last month, Google started selling its long-awaited Nexus One smart phone. Unlocked, it runs on virtually any GSM service and costs $529. With a T-Mobile contract at $80 a month, it costs $179. The Nexus One will soon be offered by Verizon. Although the unlocked version works with AT&T's network, it currently runs on the slower EDGE data network rather than AT&T's faster 3G service.
Besides Nexus One, there are other ways to get an unlocked phone. First you could ask your mobile phone operator for a code to unlock your current cell phone. You won't get one for an iPhone, but you will for many other phones. For example, T-Mobile will unlock a phone on a contract after 40 days of active service.
Secondly, many electronics retailers sell low-cost, simple unlocked phones. In Mountain View, look for a new or used unlocked phone from Mobile Kangaroo on El Camino Real.
By the way, beware of the many Internet unlocking services, which may or may not work. Unlocking a phone may not breach copyright, but it could violate the license for your phone service or phone software.
Next you need to get a phone number by buying a SIM card (note some services like Sprint don't use SIM cards). Best Buy offers many SIM cards, including the O2 Wireless SIM card for $10. On O2's network you can get a 5-cents-a-minute rate with a $30 card, but you must use up the money in 30 days or lose it. O2's advantage is that it has free international calling to over 50 countries, including Mexico.
Supermarkets, drugstores and electronics stores sell refill cards for your prepaid service, typically for $10, $20 or $40. This is where the carriers catch you out, because refill cards can expire very quickly and per-minute rates may be high. So read the fine print. On Verizon or AT&T, a refill of $100 will last one year and give you at least 400 talk minutes. Typical rates are $4 a day or 25 cents a minute.
If you normally phone where there is WiFi, then try Truphone's prepaid service that works on Google's Android (including the Nexus One), Nokia, BlackBerry and iPod Touch platforms. Truphone comes from Software Cellular Network Ltd. in the U.K., with U.S. headquarters in Mountain View. I use Truphone's iPhone app to call U.K. phones. It's free to call Skype, Truphone and Google Talk users. Truphone costs 5.1 cents a minute and the money in your account doesn't disappear after 60 days.
Truphone recently announced a single SIM card that works in both the U.K. and the U.S., saving you the trouble of swapping cards when you travel. You get local calling numbers, local rates and low-cost calls to many other countries.
If you want to use your cell phone in a corporate office, then Mountain View's DiVitas Networks brings business social networking and enterprise directory services to Android, Nokia, BlackBerry and iPhone platforms, seamlessly operating over both WiFi and cell phone networks.
If you want to call internationally with Truphone, or call in the office with DiVitas, and don't use many minutes, then you might consider an unlocked phone with a prepaid service when your contract is up.